Partisan Heterogeneity and International Cooperation

Abstract

This article analyzes the relationship between partisan heterogeneity and cooperation in international organizations. We argue that partisan heterogeneity increases distributional conflict among states during intergovernmental negotiations, thereby increasing the costs of cooperation. This decreases governments’ willingness to contribute to cooperative efforts. We test the theory against data on governments’ financial contributions to the European Development Fund. The empirical analyses robustly demonstrate that partisan heterogeneity reduces governments’ incentives to contribute to European cooperation on international development. On a more general level, we offer new perspective on the role of domestic politics in international cooperation.

Keywords

partisan heterogeneity international cooperation domestic politics European Union European Development Fund

Introduction

Partisanship affects governments’ international economic policy, incentives to comply with international treaties, participation in international peacekeeping, positions in international negotiations, and many other foreign policies. Therefore, changes in partisanship should translate into general patterns of cooperation within international organizations. Although there is much research on the influence of partisanship on foreign policy, little is known about how partisan preferences influence the depth of international cooperation. When members of an international organization engage in negotiations, how do governments’ partisan preferences influence their willingness to cooperate with each other?

We argue that the extent of partisan heterogeneity among negotiating governments provides part of the answer. If states hold heterogeneous partisan preferences, they face distributional conflict because they disagree on how to achieve a common goal: even if most governments have an interest in cooperation, partisan heterogeneity causes them to disagree on what the most important issues are and how they should be addressed. In a strategic setting, partisan heterogeneity forces individual governments either to engage in increasingly costly logrolling strategies or to implement policies that are further away from their ideal points. If partisan heterogeneity among states decreases, independent of whether this implies a leftward or rightward partisan shift, the expected cost of cooperation should decrease.¹ Consequently, increasing partisan heterogeneity should decrease states’ willingness to contribute to cooperative efforts, even if they benefit from cooperation in the first place.

To test the theory, we analyze the effect of partisan heterogeneity on the willingness of European governments to financially contribute to development cooperation through the European Development Fund (EDF) between 1977 and 2006. The EDF is the main instrument of the European Union (EU) to finance development projects, so analyzing member states’ financial contributions to it can shed a lot of light on European cooperation. Analytically, the EDF provides an interesting case for two reasons. First, the European Commission serves as the agency of the EDF. The Commission has an interest in deeper cooperation, and it is arguably more influential in shaping cooperation within the EU than multilateral agents in other international organizations. Partisan heterogeneity should be less detrimental to cooperation than in other institutions, and so our empirical test against EDF data is a stringent one. If we find that partisan heterogeneity has a negative impact on EU members’ financial contributions, this should also hold in other international organizations. Second, compared to other EU policy fields, development cooperation through the EDF is more similar to other international organizations, especially the approximately fifty multilateral aid institutions around the globe whose formal and informal procedures are very similar to those of the EDF. In the EDF, financial contributions are purely voluntary (outside of the EU budget), do not serve as a redistributive instrument, and are not influenced by the European Parliament.

The empirical analyses lend support to our theoretical argument. Greater partisan heterogeneity reduces EU members’ willingness to contribute, even accounting for other influences, and the findings are robust across various different model specifications. These findings highlight the importance of partisan heterogeneity for member states’ decision of whether or not to contribute to international organizations in the first place, thereby demonstrating that partisan heterogeneity is a fundamental aspect of international cooperation. While all international organizations have unique features, our findings are of general interest to the study of international cooperation. Research on international cooperation has largely focused on slowly changing determinants of international cooperation, such as regime type or the size of the economy (Kindleberger 1986; Milner 1997; Mansfield, Milner, and Rosendorff 2000; Lipson 2003). Only few scholars have provided explanations for more dynamic fluctuations in cooperation (Milner 2006; Milner and Tingley 2011). We show that partisan heterogeneity provides an important explanation for these fluctuations.

Partisanship, Heterogeneity, and International Cooperation

It is common wisdom that partisanship affects domestic and foreign policy formation. Whereas conservative political parties have embraced the neoliberal agenda of liberalization, many left-wing parties have emphasized the importance of social insurance and defended the welfare state against external pressures (Garrett 1998; Iversen 1999; Boix 2000; Milner and Judkins 2004). Partisan ideology also exerts influence on whether governments comply with international treaties, whether they support military interventions for international peacekeeping, and how they vote in the United Nations General Assembly (Rathbun 2004; Epstein, O’Halloran, and Widsten 2009; Grieco, Gelpi, and Warren 2009; Potrafke 2009b). In the EU, partisan ideology has been important for explaining governments’ preferences toward European integration in the Council of Ministers, the European Commission, and the European Parliament (Hix and Lord 1997; Hooghe, Marks, and Wilson 2002; Marks, Wilson, and Ray 2002; Hix, Noury, and Roland 2006; Hagemann and Hoyland 2008; Tallberg and Johansson 2008; Warntjen, Hix, and Crombez 2008).²

The extant literature shows that partisanship influences governments’ preferences toward certain policies. Most governments have an interest in cooperation, but they may disagree, based on their partisanship, about what the most important issues are and how they should be addressed. For example, both left and right governments can gain from delegating the allocation of foreign aid to multilateral institutions, but they tend to have different views about how foreign aid should be distributed to achieve sustainable economic development in recipient countries. Thus, partisan heterogeneity can cause distributional conflict about which policies should be implemented.

The relationship between partisan ideology and international cooperation is therefore more than a simple summation over member states’ partisan ideologies. Strategic interaction between governments with different partisan preferences may shape the final bargaining outcomes. Figure 1 illustrates. In the figure, three governments with different partisan preferences attempt to cooperate on a specific policy. While theory and data on partisan ideologies can help explain how states formulate their preferences (left side of the figure), a strategic analysis is necessary for understanding how international institutions aggregate these preferences into policies and outcomes (right side of the figure). The theory we now develop accounts for the strategic implications of partisan heterogeneity for the willingness of states to contribute to international cooperation.

Figure 1.

Partisanship and international cooperation.

Our theory builds on existing theories that analyze the effect of veto players and wealth heterogeneity on the efficiency of legislative decision making at the European level as well as the outcomes of Council negotiations (Hug and König 2002; Tsebelis and Yataganas 2002; Zimmer, Schneider, and Dobbins 2005; König and Slapin 2006; König 2007; Slapin 2008; Hertz and Leuffen 2011; Veen 2011). However, whereas these approaches mainly focus on particular policy preferences and outcomes of international negotiations, we are interested more generally in explaining governments’ willingness to contribute to deeper cooperation based on partisan heterogeneity in the international organization. Partisan heterogeneity itself can reduce the willingness of states to cooperate in the first place even if all parties would benefit from cooperation.

Our theory is based on several simplifying assumptions. First, we take the partisanship of governments as given. Accordingly, the main actors in our model are governments characterized by partisanship. Second, we focus on the left–right dimension. The left–right cleavage remains the most important axis of political contention in many countries. Thus, the leftist or rightist orientation of a government is generally easier to recognize than more nuanced distinctions (Hooghe, Marks, and Wilson 2002; Marks, Wilson, and Ray 2002; Warntjen, Hix, and Crombez 2008). Third, we define international cooperation as governments’ willingness to adjust their behavior through policy coordination. If governments agree to cooperate, each government contributes to international cooperation by implementing a policy adjustment, such as funding multilateral development assistance. Fourth, we assume that international cooperation is flexible enough to accommodate variation in partisan preferences. Both right-wing and left-wing governments want to cooperate, but they may disagree on what the ideal policy is. For example, while right-wing governments may generally have a stronger preference for liberalization, left-wing governments also gain from reduced tariffs through decreased consumer prices and increased employment in export industries.

Based on these assumptions, we can now analyze the effect of partisan heterogeneity on cooperation. Similar to in Figure 1, each state has a partisan government with a policy preference. Governments try to assert these preferences when they negotiate the harmonization of policies. If the international organization is composed of a relatively homogeneous group of governments with shared partisanships, it is easier to achieve a common understanding of how the problem should be solved. First, suppose two negotiating states have left-leaning preferences. They can relatively easily agree on the best solution to a problem, because these adjustments are chosen to minimize the domestic cost for left-leaning governments. Similar dynamics are to be expected when all negotiating states hold relatively rightist preferences. These states may choose a very different approach to a problem than left-leaning governments would, but cooperation should still occur. All else constant, greater partisan homogeneity should increase the willingness of states to contribute to cooperation.

As partisan preferences diverge, distributional conflict increases, and this complicates the negotiations. While governments could still cooperate by employing logrolling strategies across policies or over time, this is costly.³ If partisan heterogeneity is very high, it would be hard to find a zone of agreement to begin with. Even if a compromise exists, both left-wing and right-wing governments would probably accept the policy with regret, as a “second best” solution that could be avoided without partisan heterogeneity. Consequently, greater partisan heterogeneity should reduce the willingness of states to contribute to cooperative efforts in international organizations.⁴

In sum, even if left and right parties benefit from international cooperation, partisan heterogeneity complicates cooperative efforts. It increases distributional conflict, so achieving cooperation is more difficult. An increase in partisan heterogeneity within an international organization should reduce each state’s willingness to contribute to cooperative efforts, ceteris paribus.

Research Design

In this section, we analyze the effect of partisan heterogeneity on intergovernmental development cooperation in Western and Central Europe. Our data consist of observations for fifteen Western and Central European states between 1977 and 2006.⁵ The unit of analysis is the country-year. Since the number of countries contributing to the EDF has increased from six to fifteen, we analyze an unbalanced panel data set. It starts with nine countries in 1977 (France, Germany, Italy, Denmark, United Kingdom, Belgium, Luxembourg, Ireland, and the Netherlands) and is subsequently expanded to Greece, Spain and Portugal, and Austria, Finland, and Sweden.⁶

Dependent Variable

We measure the willingness of European states to contribute to multilateral cooperative efforts in the area of economic development in terms of financial contributions to the EDF. The EDF is the main instrument for the Central and Western European states belonging to the EU to provide development aid to the group of African, Caribbean, and Pacific countries (ACP) and the group of overseas countries and territories (OCT).⁷ The EDF budget is independent of the common EU budget. Governments independently decide how much to contribute to the EDF, and the European Parliament has no influence on the amount of contributions. Bargaining about the size of contributions takes place within the EDF committee, which is composed of all governments contributing to the EDF as well as the European Commission. The Commission serves as the agent to implement and manage decisions taken by the Committee. Each EDF is concluded for a period of five years. So far, EU members have agreed on ten EDFs (the current one running until 2013).

The EDF is a useful application of our theory because it allows us to build on the existing research and data collection efforts of EU scholars, but at the same time provides an opportunity for more generalizable statements about the effects of partisan heterogeneity on cooperation within international organizations. Most importantly, the formal and informal bargaining dynamics in the EDF committee resemble bargaining dynamics in other international organizations more closely than the bargaining dynamics in the Council of Ministers in the EU. The structures of the EDF are very similar to the approximately fifty regional and multilateral development banks, where members provide voluntary contributions which are then managed by an international agent. That is, besides the potential influence of the European Commission, questions about generalizability would not be plagued by the influence of the European Parliament on the depth of cooperation.

Applying the theory to the EDF also allows us to analyze the effects of partisan heterogeneity in a particular policy field: international cooperation in providing sustainable economic development in the least developed countries in the world. Empirical research shows that both left and right parties have an interest in developmental issues, but that they may have diverging interests about how to conduct it (Noel and Therien 1995; Schraeder, Hook, and Taylor 1998; Boix 2000; Thérien and Noel 2000; Lancaster 2007). There are many ways to advance economic development, from public infrastructure and education to privatization and liberalization, and the allocation of financial resources through the budget has distributional consequences for different constituencies. In addition to economic development, foreign aid can be used for security purposes, to promote economic ties, to support development of the welfare state in developing countries, for environmental conservation, or to buy votes in the United Nations and other multilateral fora. The partisanship of donor governments does not only determine who gets foreign aid but also how much is given to what end. When providing foreign aid through multilateral aid institutions, governments usually pursue goals similar to the ones they pursue when providing aid bilaterally (Schneider and Tobin 2013). For these reasons, we expect that an EDF member has more reason to believe that national contributions are put to good use if other EDF members hold similar partisan preferences. Increasing partisan heterogeneity in the EDF committee should therefore, all else equal, induce EDF members to contribute less to the EDF.

EDF Contributions is measured as the log of each member’s annual contribution to the EDF budget in millions of constant (2007) US dollars. In addition to total contributions, we will present results for per capita contributions to the EDF. Data are available from the Organization for Economic Cooperation and Development (OECD) development statistics.

Contributions to international cooperation could also be nonfinancial: does a country vote in favor of a common policy, provide equipment, and adjust domestic policies or regulations? What is the extent to which a country is willing to give up sovereignty? Whereas partisan heterogeneity should affect nonfinancial contributions as well, a measure of financial contributions provides us with a measure of the willingness of governments to contribute to the agreed upon policies that is easily observable across members and over time. At the same time, analyzing financial contributions to cooperation is a hard test for our theory because governments make decisions about the size of their contributions only every five years. Whereas there usually is some room to change contributions within each of these five-year EDFs, it is relatively limited. Using data with annual observation therefore underestimates the effects of the explanatory variables. Indeed, as we show below, the effect of partisan heterogeneity on EDF contributions is stronger when we estimate the models using EDF period data instead of annual data.

Measuring Partisan Heterogeneity

To code partisan heterogeneity, we proceed in three steps. First, for a measure of a government’s partisanship in any given year, we rely on partisanship data from Warntjen, Hix, and Crombez (2008). They measure each member’s partisan position based on the Comparative Manifesto Project (CMP) data. The CMP scores are based on manual coding of partisan “manifestos.” Coders assign quasi-sentences (sentences with exactly one statement or message) to one of the fifty-six policy categories. To create a left–right scale, twenty-six relevant policy categories, such as those pertaining to economic regulation, are used. To code a party’s position on this left–right scale, the percent of left–wing statements is subtracted from the percent of right-wing statements, with negative (positive) numbers indicating left-wing (right-wing) preferences.⁸ The raw CMP partisan score is used to create a partisan score for coalition governments. This score is weighted by each party’s number of ministers in the cabinet. The more ministers a party has in government, the more important its partisan value for the calculation of the member partisan score.

Second, we weigh the coalition score by the EU member’s proportion of formal votes to account for differences in political impact on cooperative outcomes. Even if decision making is typically made by consensus in the EDF committee, research on bargaining in the EU has demonstrated that voting weights do matter for the final outcome (Thomson et al. 2006).

Finally, we use the weighted coalition score to calculate a measure of partisan heterogeneity in the EDF committee. Partisan Heterogeneity is measured as the standard deviation of the average CMP score for EU members each year.⁹ It would also be possible to use the range of the partisanship in the EDF. We present estimations with such a measure in the robustness section and find no difference in the effect.¹⁰

Figure 2 plots Partisan Heterogeneity and total EDF contributions over time. The graph illustrates that whereas partisan heterogeneity has generally declined, total contributions to the EDF have increased. Most importantly, the graph provides at least some support for the argument that the partisan heterogeneity impacts EDF contributions on an annual or EDF period level. In the models, we will control for time effects to ensure that our results are not based on the general trend in these two variables.

Figure 2.

Partisan heterogeneity and total European Development Fund (EDF) contributions.

Control Variables

We control for several confounding factors.¹¹ First, we use the per capita gross domestic product (GDP) as a percentage of the EU average to account for the fact that richer countries should be able to make larger contributions than poorer countries (Per Capita GDP [EU = 100]). The data are from Eurostat. Second, we include a measure for each EU member’s bilateral foreign aid (as a percentage of its GDP) to control for variation in countries’ general willingness to provide foreign aid (Bilateral Aid [% GDP]). The data are from the OECD Development Statistics. Third, we include an independent measure of a government’s bargaining strength in the EU. We thereby follow Aksoy (2010) and calculate Representation by dividing the number of votes a government has by its population and then dividing this by the average per capita votes in the EU as a whole.¹² Fourth, it seems plausible that countries under economic difficulty are less willing to contribute. We use a country’s unemployment rate to account for this (Unemployment Rate). The data are from Eurostat. Fifth, we control for the per capita amount of financial resources that a country receives from the European budget (Per Capita EU Receipts). Finally, we estimate models that include a lagged dependent variable (LDV) and a time trend.¹³

Descriptive statistics for all variables are presented in Table 1.

Table 1.

Descriptive Statistics.

	N	M	SD	Min	Max
EDF contributions (log)	336	4.7	1.4	0.9	6.9
EDF contributions (per capita)	336	7.9	4.4	0.8	32.6
Partisan heterogeneity	420	1.6	0.6	0.6	2.7
Mean EU partisanship	420	0.2	0.4	−1.0	0.8
Per capita GDP (EU = 100)	429	105.3	38.9	26.7	301.2
Unemployment	412	7.8	3.6	0.5	21.3
Representation	389	−14.6	1.0	−15.9	−11.7
Bilateral aid (log)	420	6.9	1.4	2.2	9.2
Per capita EU receipts	374	14.7	4.7	9	25

Note. EDF = European Development Fund; GDP = gross domestic product; EU = European Union.

Model Specification

The data are time-series-cross-sectional. To deal with potential problems of panel-heteroscedasticity and serial correlation, we estimate unbalanced Prais-Winsten panel regression models with country-fixed effects and panel-corrected standard errors (PCSE). The model is specified as:¹⁴

Y_{i t} = α + β P_{i t} + γ X_{i t} + v_{i} + u_{i t},

where $Y_{i t}$ denotes the log of EDF contributions for each country-year, $P_{i t}$ is the partisan heterogeneity variable, $X_{i t}$ is the vector of explanatory and control variables, $α$ is the constant, $v_{i}$ are the unit effects, and $u_{i t}$ is the error term. The respective coefficient vector for $P_{i t}$ and $X_{i t}$ are denoted by $β$ and $γ$ .

We include country-fixed effects into the regression models because the Hausman test suggests that the random effects model and a simple pooled ordinary least squares model would render the coefficients inconsistent and biased. Besides eliminating bias, an additional advantage of this approach is that the inclusion of time-invariant country effects allows us to interpret the coefficients as the effect of a change in, for example, partisan heterogeneity on a change in contributions. Using fixed effects also implies a first-differencing of the independent variables. This is important because our main independent variable is trended. Second, the Durbin-Watson statistic of an untransformed model points to a serial correlation of the error terms. We use a panel-specific first-order autoregressive (AR1) process to deal with this problem, but check for the robustness of the results by estimating the main models with a LDV.¹⁵ We also present models with a time trend to check whether the partisan effect is due to an increase of partisan homogeneity over time. Third, all models have PCSEs to correct for panel heteroscedasticity as well as for contemporaneously correlated errors across panels. In addition, using PCSEs deals with the fact that the number of panels increases over time.

Empirical Results

Table 2 presents the main results.¹⁶ Model 1 is the basic model with total EDF contributions (logged) as dependent variable, model 2 uses a per capita measure of the dependent variable, model 3 uses a LDV instead of a Prais-Winsten transformation, and model 4 includes the time trend. Finally, model 5 provides results of an estimation that is based on average contributions over each EDF period.¹⁷ The model fits the data very well with the Wald test producing highly significant results. In addition, the model explains almost 90 percent of the variation in the data.

Table 2.

Partisan Heterogeneity and EDF Contributions.

	Model 1 (Main)	Model 2 (per capita)	Model 3 (LDV)	Model 4 (time trend)	Model 5 (period)
Partisan heterogeneity	−0.235** (0.069)	−1.529** (0.571)	−0.210** (0.061)	−0.321* (0.167)	−0.351** (0.089)
Per capita GDP (EU = 100)	0.005** (0.002)	0.012 (0.018)	0.004* (0.002)	0.005** (0.002)	−0.000 (0.002)
Bilateral aid (% GDP)	54.556* (29.663)	428.950* (234.464)	35.126 (22.342)	55.386* (29.182)	128.631** (28.541)
Council representation	0.033 (0.026)	−0.142 (0.241)	0.018 (0.024)	0.030 (0.025)	0.052* (0.027)
Unemployment rate	0.034** (0.016)	0.168 (0.115)	0.029** (0.013)	0.035** (0.016)	0.035* (0.019)
Per capita EU receipts	361.525 (238.054)	5,600.314** (2,855.903)	215.746 (234.673)	366.926 (233.071)	295.647* (161.030)
LDV			0.099 (0.111)
Time trend				−0.007 (0.013)
Constant	5.354** (0.379)	5.509** (2.532)	5.020** (0.757)	5.613** (0.541)	5.837** (0.361)
Observations	304	304	293	304	66
R ²	0.899	0.725	0.943	0.903	0.976
Number of countries	15	15	15	15	15
χ²	5,260	580.3	99.89	6,505	12,137

Note. EDF = European Development Fund; EU = European Union; GDP = gross domestic product; LDV = lagged dependent variable.

Standard errors in parentheses. **p < .05. *p < .10.

Turning to the substantive effects, we find support for our theory across all model specifications. As the heterogeneity of preferences within the EDF committee increases, governments provide less funding for the EDF. Specifically, an increase in partisan heterogeneity of one standard deviation decreases a given government’s contributions to the EDF by 23.5 percent. The effect is even stronger in the models controlling for the time and membership trends and it is robust over all model specifications. Thus, the more homogeneous the EU, the greater the contributions (per capita and total) (1) in the basic model; (2) in the LDV model; (3) in the model that controls for the time trend; and (4) in the model that uses EDF periods instead of annual data.¹⁸ It is worth noting that the effect of Partisan Heterogeneity increases to 35.1 percent in the period model. As discussed above, governments have more leverage to change the size of their contributions at the beginning of each EDF period than within these periods. But the results in model 1 demonstrate that governments still have some leverage on an annual basis. The existence of an effect in the annual specifications therefore provides strong support for the influence of partisan heterogeneity on cooperation in the EDF.

The effects of the control variables are interesting as well. As expected, richer countries tend to contribute more to the EDF. However, they do not appear to give more on a per capita basis. In addition, governments that provide large percentages of their GDP for bilateral development aid, contribute larger amounts to the EDF.¹⁹ Surprisingly, countries with high unemployment rates contribute more to the EDF than countries with low unemployment rates, ceteris paribus. This effect is due to the country-fixed effects. Excluding the effects render the variable positive and statistically significant. Consequently, contributions to the EDF do not depend on the economic situation within the country as measured by the unemployment rate. Finally, countries that receive more financial support from the EU are not more or less likely to contribute to the EDF. Interestingly, they contribute more to the EDF on a per capita basis. This positive relationship most likely owes to small rich countries that also receive relatively large financial resources from the EU if measured per capita.

In sum, the quantitative analysis shows that partisan cleavages in the EU reduce contributions to the EDF. This provides some support for our theoretical argument. Since right- and left-wing parties generally have different preferences about how to spend foreign aid, partisan heterogeneity reduces the expected benefits that EDF members can reap from cooperation. Since the partisan effect may be fragile to different model specifications, we conducted further tests to check for its robustness. The findings of these tests can be found in the online appendix.

Alternative Measures of Partisan Heterogeneity

To scrutinize the robustness of the results, we first tested whether the effect of Partisan Heterogeneity is conditional on particular values for the average partisan ideology in the EDF. We find that the effect of partisan heterogeneity on cooperation in the Committee does not depend on the average partisanship in the EDF committee.²⁰ EDF members are more likely to contribute if partisan heterogeneity decreases, regardless of the average partisanship in the EU. It is important to note two important caveats here. First, the null effect of Partisan Mean is due to the fact that all EDF members have a basic incentive to cooperate on development-related policies. We would expect Partisan Mean to matter when the common policy in itself is supported by left (right) governments, but opposed by right (left) governments. Second, although we find that partisan heterogeneity reduces cooperation regardless of the partisan shift, our results say nothing about the content of the international cooperation. Indeed, we would expect that EDF policies would be quite different for EDFs that are composed of purely right-wing or purely left-wing governments.

In addition to analyzing the conditional effect of partisan heterogeneity, we measured Partisan Heterogeneity as the range of governments’ partisan positions. Again, the results are robust to our main measure of partisan heterogeneity. Third, we use the partisan measure proposed by Potrafke (2009a) and the partisan measure based on expert judgment data (Castles and Mair 1984; Benoit and Laver 2006; data from Warntjen, Hix, and Crombez 2008). The Potrafke (2009a, 112) measure “places the cabinet on a left-right scale with values between 1 and 5. It takes the value 1 if the share of governing right wing parties in terms of seats in the cabinet and in parliament is larger than 2/3, and 2 if it is between 1/3 and 2/3. The index is 3 if the share of center parties is 50 percent, or if the leftwing and rightwing parties form a coalition government not dominated by one side or the other. The index is symmetric and takes the values 4 and 5 if the leftwing parties dominate.” The expert measure is based on raw data from the Chapel Hill expert survey (Steenbergen and Marks 2007). Ideology on a left–right scale is measured using surveys which ask country experts to assign a left–right position for each government in a number of countries on a scale from 0 (extreme left) to 10 (extreme right). A score of 5 indicates a party in the center. Experts choose the ideological position that best describe the party’s overall ideology.

The main finding for partisan heterogeneity is robust to using the Potrafke measure, but not to using the expert judgment data. The coefficient for Partisan Heterogeneity (Expert) is still negative but not significant at conventional levels (the effect is significant on a 10 percent level in a one-tailed test). This result is somewhat surprising since previous research indicates that the differences between these two measures should not loom too large (McDonald and Mendes 2001; Benoit and Laver 2006; Klingemann et al. 2006; Warntjen, Hix, and Crombez 2008). For example, Warntjen, Hix, and Crombez (2008) demonstrate a high and statistically significant correlation between expert judgment data and the CMP data on left–right party positions in the EU. Analyzing our data, we observe inconsistencies between the two measures in the period between 1991 and 1994. If we estimate the model excluding these years, Partisan Heterogeneity (Expert) exerts a negative effect on EDF contributions which is significant on the 5 percent level (two-tailed test).²¹ In fact, the main inconsistency seems to lie in the years 1993 and 1994. Excluding these two years yields a significant effect of Partisan Heterogeneity (Expert) at the 10 percent level (two-tailed test).

Types of Heterogeneity

Our analysis focuses on the effect of partisan heterogeneity, but the literature discussed above suggests that other conflict dimensions could also have important impacts on the willingness of countries to contribute to the EDF. To test for the influence of other types of heterogeneity, we first included a measure of income heterogeneity. Income Heterogeneity is measured as the standard deviation of the logged per capita GDP of EDF members for each year. Data are from Eurostat. Consistent with the literature on conflict dimensions in the EU, we find that income heterogeneity in the EDF significantly decreases a government’s contributions to the EDF. In other words, poor and rich countries tend to have different preferences about how foreign aid should be allocated. However, it is important to note that the coefficient of Partisan Heterogeneity is still significant. That is, income heterogeneity matters but it does not drive the effect of partisan heterogeneity. Second, we used two different variables to measure heterogeneity in EDF members’ support for European integration. Heterogeneity in EU support could matter because the EDF is an instrument that was created through the EU and represents the interests of the majority of EU members. Governments in which EU support is high could pursue different policies from governments in which EU support is very low. First, we measured the standard deviation of countries’ public support for European integration. Data are from the Eurobarometer. Second, we measured the standard deviation of a countries’ government support for European integration. Data are from the Partisan Manifesto Project. Whereas heterogeneity in public support decreases contributions to the EDF, heterogeneity in government support does not exert a significant influence on contributions to the EDF. The findings are interesting because decision making in the EU is typically characterized as elite-driven process. These results suggest that, at least within the EDF, public opinion shapes the bargaining positions of governments at the international level.

A Theory of Partisan Heterogeneity beyond the EDF?

We find that partisan heterogeneity reduces the willingness of European states to contribute to international cooperation on economic development. But what does this mean for the influence of partisanship on cooperation in other international organizations? All international organizations, and perhaps the EU in particular, are complex entities. Further analysis is necessary to establish a more general effect of partisan heterogeneity. Nevertheless, it is useful to discuss some of the unique features of the EDF and their influence on the theoretical relationship.

The greatest limitation to generalizability is that integration in Europe has progressed faster than in other international organizations. Governments have delegated powers in a large number of policies and the two supranational institutions, the European Commission and the European Parliament, exert great influence on decision making. The EU deals with more policies and it has granted more power to its supranational agency than any other international organization. Both the Commission and the Parliament are considered more prointegrationist than EU member governments. Therefore, they should produce bias in favor of cooperation. Along similar lines, the large number of policy fields in the EU provides ample opportunities for logrolling. Indeed, previous work on EU decision making has emphasized logrolling in the Council (Heisenberg 2005; König and Junge 2009; Mattila and Lane 2001; Aksoy 2012). The negative effect of partisan heterogeneity should therefore be stronger in other international organizations. In addition, cooperation within the EDF is somewhat different to typical cooperation in other policy fields of the EU. First, the European Parliament has no influence on decisions. Second, contributions are purely voluntary. Its institutional features therefore resemble other institutions, and in particular regional and multilateral aid institutions (of which there are over fifty by now), more closely than the EU itself.

A second potential issue is the strong consensus norm in the EU. On one hand, the consensus norm increases the cost of cooperation for states that could assert themselves if decisions were made by majority rule. On the other hand, it assures that weaker states are not forced to accept policies that are far away from their ideal policies. For any application beyond the EU, one would therefore have to carefully analyze how preferences are aggregated through existing formal and informal institutions. However, as we noted above, negotiations in many other international organizations are based on consensus norms. Whereas the reliance on these norms may vary across institutions, the existence of this norm across institutions provides a useful foundation for comparative analysis.

Beyond the specific characteristics of the EU, our argument on the effect of partisan heterogeneity depends on the presence of benefits for cooperation for both parties and on salient distributional conflict. First, our argument is not applicable when some parties have no incentives to cooperate to begin with. In such cases, we would expect that increasing partisan homogeneity results in greater contributions only if the shift of partisanship is toward those parties who can gain from cooperation but would result in lower contributions if the shift of partisanship is toward those parties who cannot gain from cooperation. In other words, the effect of partisan heterogeneity on cooperation would be conditional on the mean of partisanship in the international organization. Second, our argument is only applicable in situations where partisan heterogeneity leads to distributional conflict. If Fearon (1998) is correct to argue that distributional conflict is central to international cooperation, our results on the importance of partisan alignment are relevant. If partisan heterogeneity amplifies distributional conflict, the cost of bargaining between states may be reduced under partisan homogeneity.

Finally, the comparability of partisanship across countries presents a challenge. For example, conservative partisan ideologies in Scandinavia are different from conservative partisan ideologies in the United States. Testing our argument in international organizations, such as the World Trade Organization, would thus require more fine-grained measures of partisanship. This could also be a problem for our test against EU data. If partisanship were not comparable across EU countries, our measure of partisan heterogeneity would be biased toward greater homogeneity. For example, phases when the EU consists of mostly left parties stand for homogeneity in our measure, but in reality preferences could be much more heterogeneous. Consequently, our measure would cause attenuation bias and lead us to underestimate the negative effect of partisan heterogeneity.

These caveats notwithstanding, we can think of several potential applications of our argument. Within the European context, we expect our finding to hold for cooperation in the EU more generally. For example, a central provision of the treaty establishing the European Economic Community in 1957, for instance, calls for a development of a common social and economic policy. For many years, however, EU member states did little to give effect to this agreement (Nugent 2006). The delay was in large part due to a partisan split within the Council of Ministers on socioeconomic issues. Whereas socialist governments promoted a focus on social cohesion, employment, investment, and infrastructure, conservative governments put much more emphasis on a mixture of free market economics that would allow for state intervention only to facilitate economic recovery (Hix and Lord 1997, 192).²² It was not until the shift from a largely heterogeneous Council, in which socialist and conservative parties had about equal number of ministers, to a very homogeneous Council, in which socialist parties had captured thirteen of the fifteen governments parties, that the negotiations moved toward a formal agreement in Lisbon in 2000 (Tallberg and Johansson 2008, 1227).

The liberalization of the European electricity market also points to the importance of partisan heterogeneity. The first concrete step toward deregulation at the regional level was a 1988 Commission study which identified major obstacles to an internal market in the electricity sector (Eising 2002, 92). The Commission put forward an ambitious liberalization proposal, emphasizing third-party access and the dismantling of the electricity grid monopolies. The proposal was similar to Margaret Thatcher’s deregulation efforts in the United Kingdom, and so it unsurprisingly was supported by the right-wing Thatcher government (Eising 2002, 93). In France, however, the ruling left-wing coalition opposed the move (Bartle 2002, 8–11). Factors such as the political influence of major utilities, environmental considerations, and learning at the European level also played an important role (Bartle 2002; Eising 2002). President Mitterand’s government introduced a less ambitious Single Buyer model which induced much less competition than the Commission’s proposal. In Germany, the conservative Kohl government initially opposed liberalization, in large part because energy utilities “were united in [their] arguments that competition should not be introduced because of the importance of supply security and the special technical factors” (Bartle 2002, 9). In a few years’ time, however, “the Federal Economics Ministry . . . endorsed the EU reform because it expected liberalization to bring about a major increase in sectoral efficiency and German industrial competitiveness” (Eising 2002, 112). In the European Parliament, the (left-wing) Socialists opposed the Commission’s proposal while the (right-wing) European People’s Party supported it. It was only in 1996 that the United Kingdom, now ruled by the government of a more moderate conservative Prime Minister, John Major, agreed on a compromise that would include the French proposal. Soon after the election of the conservative Jacques Chirac as the President of France in 1995, the country also agreed to support the current proposal. With all three major European powers ruled by conservative governments, the Council proposal was finally accepted by the European Parliament without amendments.

Outside the European context, many multilateral aid institutions, such as the World Bank and the International Monetary Fund, allocate resources for public projects that have distributional consequences. Measuring the effect of partisan shifts on financial cooperation and multilateral development assistance is a promising empirical application of our theory. Similarly, our theory might be particularly relevant to the United Nations. Whereas virtually all states agree that the United Nations should provide “collective security,” they are often in disagreement on how aggression is to be deterred and, if necessary, confronted. The United Nations also frequently dispatches peace-keeping missions that depend crucially on contributions and troops from member states.

To the degree that partisanship determines how states view peacekeeping, our theory provides new insights into the underlying dynamics even outside of the UN framework. For an example, partisan heterogeneity played an important role in the cooperation on intervention in Iraq after 9/11. On a North Atlantic Treaty Organization summit in November 2002, President Bush announced that the United States would lead a “coalition of the willing” to disarm Saddam Hussein’s Iraq. Although a number of countries, most ruled by conservative governments, initially signed up, the coalition rapidly disintegrated. After winning the parliamentary elections in Spain, the new socialist Prime Minister José Luis Rodríguez Zapatero left the coalition and brought Spanish troops home in April 2004.²³ In Italy, the new leftist Prime Minister Romano Prodi announced in June 2006 that the country would withdraw all Italian troops from Iraq by the end of the year.²⁴ In November 2007, after a landslide victory in federal elections, the incoming Australian Prime Minister and Labor Party leader, Kevin Rudd, announced that Australia would also pull all troops from Iraq.²⁵ In each case, a right-wing government lost power to a left-wing government thereby increasing conflict over how intervention should be conducted. Specifically, whereas few advanced democracies disagreed on the need to prevent Saddam Hussein from acquiring weapons of mass destruction, left-wing parties emphasized the role of the United Nations and economic sanctions over the immediate use of military force against Baghdad.

Partisanship also appears particularly relevant for the formation of preferential trading agreements. Left-wing and right-wing constituencies might disagree on the aims and scope of liberalization, as factor endowments and the terms of liberalization redistribute wealth and trigger changes in relative prices. Given the recent profusion of such agreements, our theory can help understand the timing and durability of international trade cooperation. After his election as the president of Bolivia in 2006, the leader of the Movement for Socialism, Evo Morales not only rejected the preferential trade agreements that the United States had promoted in Latin America but also signed several important trade and security pacts with Venezuela and Cuba to form what he dubbed the “axis of good.”²⁶ Given that Bolivia had begun to negotiate an agreement with the United States in 2004, this was a major policy shift.²⁷ As Bolivia turned left, it abandoned trade cooperation with the conservative administration of the United States, as the preference distance between the two governments increased. Most importantly, however, it did not abandon international trade cooperation, but rather increased cooperation with governments that had similar preferences about how and under what conditions trade liberalization should be conducted. Transatlantic cooperation to mitigate climate change may provide another illustrative example. Given that conservative parties have generally, and especially in the United States, adopted a hostile stance toward climate cooperation, a reduction in partisan heterogeneity through a strong rightward shift would probably have a negative effect on climate cooperation (Laird and Stefes 2009; McCright and Dunlap 2003). By contrast, a strong leftward shift could increase governments’ willingness to form effective climate agreements and undertake the domestic actions necessary to implement them.

Conclusion

This article analyzed the effects on partisan heterogeneity on international cooperation. Although governments have incentives to cooperate, they are more likely to agree on mutual policy adjustments if they share a common partisan ideology. Empirically, we found that governments contribute less to the EU budget and development assistance if partisan heterogeneity is great.

The empirical analysis of partisan heterogeneity and development cooperation in the EU is merely a first step toward explaining partisanship effects in international organization. And while the discussion above indicates that our results may be generalizable to other international organizations, further empirical analysis would be desirable. We hope that our article provides a theoretical and empirical basis that future work can build upon.

In addition, the theoretical framework lends itself to interesting analytical extensions and variants. For one, the interactions between partisan heterogeneity and other preference factors, such as public opinion and sectoral interest groups, hold promise. Consider, for example, European electricity deregulation. How did the effect of partisan ideology on governments’ negotiation positions depend on the competitiveness and political clout of their energy utilities? In the case of EU and IMF emergency loans to Greece since the 2008 financial crisis, did partisan heterogeneity play a role in influencing countries’ decisions to participate? Globally, do partisan preferences condition the effects of factor endowments and industry groups on multilateral trade negotiations? More generally, how does the effect of partisan heterogeneity on negotiation outcomes and cooperation depend on the political–economic context? An interactive theory of partisan heterogeneity and other determinants of state preferences would provide answers to these questions.

Footnotes

Acknowledgments

A replication package is available on the journal’s website. For helpful comments on previous versions, we thank Niklas Potrafke, Andreas Warntjen, Camber Warren, Narayan Subramanian, and the participants of the HALBI workshop at University of California, San Diego.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Schneider gratefully acknowledges financial support from the UC Berkeley European Union Center of Excellence.

Notes

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