Filling the Amendment Tree: Majority Party Control,Procedures,and Polarization in the U.S. Senate

Abstract

Harry Reid is often lauded by fellow Democrats as one of the most powerful Senate Majority leaders in modern history. One tactic that he used to usher in legislation was a parliamentary procedure known as “Filling the Amendment Tree.” Amendment trees are diagrams that demonstrate the amendment process for legislation, but Reid often limited the number of amendments that could be offered on a piece of legislation using this procedure. From the majority’s perspective, this procedure helps usher in legislation and protects vulnerable moderates from having to vote on controversial legislation. Still, others argue that the restrictive procedure limited the ability of moderate Democrats to distinguish themselves from their party leadership, making them vulnerable to attacks. In this article, I find that filling the amendment tree did not limit moderate Democrats from proposing amendments. In fact, although moderate Republicans shied away from the process of filing amendments in protest, there was no statistical relationship between ideology and the number of amendments filed for Democrats. Still, upon examination of voting data, the use of the procedure homogenized the voting records of moderate Democrats in the 112th and 113th Congresses. Furthermore, it forced moderate Republicans to vote more often with the Democrats in each of the Congresses in which Reid employed the procedure.

Keywords

Congress Senate parliamentary procedures filling the amendment tree Harry Reid

The Senate is often referred to as “the world’s greatest deliberative body.” That is a phrase that I wince at each time I hear it, because the amount of real deliberation, in terms of exchange of ideas, is so limited.

—Senator Jeff Merkley (D-OR) (Packer, 2010).

Senator Merkley’s objection to the often-used description of the U.S. Senate as the greatest deliberative body is descriptive of the general state of the Senate today. Plagued with increased polarization and partisan maneuvering, the modern Senate has struggled with the legislative process. Indeed, ideologically, the Senate players have moved to their respective poles leaving few moderates willing to cross party lines (Bond, Fleisher, & Stonecash, 2009; Mayhew, 2005; McCarty, Poole, & Rosenthal, 2006; Sinclair, 2006; Theriault, 2008). Still, Lee (2009) finds that the process is increasingly partisan, as each caucus maintains homogeneity on voting in the modern era.

Regardless of the nature of division, the Senate has transformed from an individualistic body known for deliberation and moderation to one of division and obstruction. In their book on agenda control, Den Hartog and Monroe (2011) paint the picture of an adversarial Senate in which the majority party has considerable strategic advantages over the minority party. As Smith (2007) notes, the increase in division has led to a more party and leadership-centric chamber in which members of both the majority and minority coalesce around the leadership. Indeed, members of the minority party have often formed a monolithic bloc in opposition of the majority party. Even presidents focus their attention mainly on party leaders rather than pivotal voters (Beckmann, 2009). Perhaps, the most well-known method of obstruction is the filibuster, in which a minority of 41 senators can delay or obstruct voting on legislation indefinitely (see Koger, 2010; Wawro & Schickler, 2007). Indeed, as Koger (2010) finds in his book, the number of filibusters used in the Senate has steadily increased since the 1960s. Another method of obstruction is the proposal of amendments, an unregulated aspect of lawmaking when compared with the United States House of Representatives. Unlike the House, Senate rules do not prohibit the number of amendments proposed nor do they restrict the subject matter of the amendments. The minority can use amendments to not only affect the bill substantively with policy but they can also propose “poison pill amendments,” or amendments that are difficult for members of the majority party to vote on (Beth, Heitshusen, Heniff, & Rybicki, 2009). Saxby Chambliss, a Republican from Georgia admitted,

. . . the fact of the matter is, too, that we have some folks who are bound and determined to come up with some wild and crazy amendments rather than doing the business we were sent here to do in a very serious way. (Warren, 2014)

To combat this, former Senate Majority Leader Harry Reid used a procedure called, “Filling the Amendment Tree,” which effectively limited the number of amendments proposed to legislation, and in many cases, left the minority process out of the legislative process entirely.¹ Although other majority leaders used the procedure, Reid filled the amendment tree at a greater rate than any of his predecessors. In the period between 2006 and 2012, Reid used the procedure 50 times and went on to use the procedure in total, 95 times (Raju, 2015). In comparison, his predecessor, Bill Frist (R-Tennessee) used the procedure 6 times during the 109th Congress (Beth et al., 2009) and only 12 times in his entire reign as majority leader (Darling, 2012).

The argument, of course, could be made that the use of the procedure helped safeguard much of the Democratic agenda, including the then President Obama’s ambitious legislative agenda. Indeed, the argument could also be made that the procedure protected vulnerable moderates from having to vote on controversial amendments proposed by the opposition (see, for example, Den Hartog & Monroe, 2011) who find that procedural moves by the majority party are often used to protect vulnerable moderates). Smith (2010) also finds that filling the amendment tree not only protected legislation, but was also used by the majority leader to stall the amendment process to buy time to negotiate with the opposition. Still, filling the amendment tree may have had negative repercussions on members of the Democratic Caucus. Indeed, Frances Lee (2009) argues that floor amendments allow individual senators to move legislation toward their own preferences, help senators shape public perceptions on performance, and can be used for partisan electoral campaign purposes in which the minority party can critique the majority. To protect the integrity of the legislation, Reid not only limited participation from the minority party, but also centrists who could have used the process of proposing amendments to signal their constituents that they were attempting to move legislation to their preferred ideological point.

With the inability to propose ideologically distinct amendments, the voting record for many vulnerable senators looked remarkably homogeneous to the party leadership. In the 2014 midterm elections, moderate Democrats Mark Pryor (D-Arkansas) and Mark Begich (D-Alaska) were attacked for voting their party line. Former centrist Senator Olympia Snowe (R-ME) remarked that the inability of moderate senators to get amendments onto the agenda was “shocking” (Bolton, 2014).

In this article, I examine the effects of filling the amendment tree on the legislative behavior of moderate senators. By filling the amendment tree, Reid effectively cut both parties, including his colleagues and the electorally vulnerable moderates of his party, out of the legislative early game of amending legislation. However, by looking at the amendments submitted for consideration, I find that moderate Democrats were no more or less likely than their colleagues to protest the procedure. Indeed, it was Republican moderates who were much less likely to submit an amendment when the procedure was used whereas their more conservative counterparts filed amendments in an act of protest. The use of the procedure did however likely contribute to homogenizing the voting record of senators who relied on “maverick” or centrist voting records to win reelection. Indeed, the difference in voting records for moderate Democrats and their more ideological colleagues was statistically insignificant. This in turn inhibited the ability of moderate Democrats to distinguish themselves from their party in a meaningful way—a crucial aspect of campaigning for cross-pressured or red state Democrats. As a result, although the procedure safeguarded Democratic legislation, it may have had electoral ramifications in that it contributed in the homogenization of voting records for moderate senators.

The article proceeds as follows. I begin with a description of how the majority leader fills the amendment tree and how the procedure works. Then I examine the theoretical reasons for what we should expect in terms of legislative participation. I follow this with an empirical look at the amendment process and voting records. I conclude with implications for the study and suggestions for future research.

Senate Procedures

The U.S. Senate has traditionally been known as a legislative chamber with few rules governing its members. Compared with the House of Representatives, which has a strong leadership structure and a distinct and rigid set of rules, the Senate is comparatively a “wild west” of sorts with few restrictions on minority party participation (or interference for that matter). Indeed, the intentions of the framers is summarized by James Madison’s words to Thomas Jefferson explaining that the Senate was to be the “great anchor of government” and to the framers explained that the Senate would be a “necessary fence against the fickleness and passion” of the American public and House of Representatives (U.S. Senate, 1787). As such, one of the aspects of the Senate that allows for this sort of anchoring is the ability for any senator to propose an amendment of (nearly) any topic.

For any senator, this is a tool to move the policy that is being debated to their preferred policy location. However, it is also an avenue for the minority party to interfere in the legislative process and cause problems for the majority party. For example, in 2014, on a bill that would extend unemployment benefits, Republicans attempted to propose a number of nongermane amendments. Harry Reid, the Senate Majority Leader, described the amendments as follows:

There are more than two-dozen amendments on this bill alone dealing with Obamacare, repealing it in different ways. Several other amendments have been singled out that we have before the body to attack the administration’s efforts to protect the environment. The protests of Republican senators to the contrary notwithstanding, these amendments show that the other side of the aisle is not serious about unemployment insurance benefits . . . What are they trying to do? Kill extended unemployment benefits.²

In this particular example, Reid astutely presumes that the Republican amendments have little to do with moving the policy to a different location, but instead there are efforts to get the votes of vulnerable Democrats on the record for controversial votes like repealing Obamacare or the environment—issues that are unpopular in deeply red states. This was not an isolated case. Indeed, in his book on the changing dynamics of the U.S. Senate, Stephen Smith (2010) notes that since 2005, the Senate has devolved into an institution that is wrought with “partisan procedural entanglement.” One of the main causes of this is the minority party’s ability and more importantly, willingness to use, among other procedural tactics, amendments and debate to keep the chamber from completing its work on a measure.

To protect against this sort of obstruction, the majority leader used a relatively little used procedure called filling the amendment tree. As mentioned, under Senate procedural rule, any senator can propose any amendment, regardless of content, to any bill (in nearly all cases). However, the process does have some structure which limits the type of amendments that can be pending at the same time. For example, if there is an amendment to strike text from the bill, then a proposal to amend the text to the bill should be considered before the amendment to strike the text is considered (Beth et al., 2009; Smith, 2010). To organize this, the Senate parliamentarian diagrams the amendments on a “tree” in slots allotted to each amendment proposed. An amendment proposed to amend the content of the bill is listed as a first-degree amendment, or an amendment perfecting the actual bill on the agenda. Senators can then propose amendments to either amend the first-degree amendment, or replace or substitute the first-degree amendment—these are called second-degree amendments. On most bills, this limits the number of first- and second-degree amendments to a total of 11 (Mimms, 2014). As the majority leader enjoys the right of first recognition, the leader can fill every branch of the amendment tree with amendments that affect the content of the bill infinitesimally.³ With every branch filled, a senator would require unanimous consent to propose a new amendment or have one of the previous amendments disposed of (Beth et al., 2009). This allows the majority leader to prevent other senators from proposing further amendments, but importantly, does not limit debate unless the leader is able to invoke cloture on the bill.

However, if cloture is invoked, then every amendment proposed after cloture must be germane to the bill, in which the presiding officer can rule any amendments as nongermane, thus protecting the integrity of the bill and, in theory, the majority caucus from taking difficult votes. Indeed, this is the procedure that Reid used to block Republican amendments in the aforementioned unemployment benefits extension bill. To stall the amendment process, Reid offered 11 amendments, each addressing the enactment date of the law, none of which passed (Mimms, 2014).

Although he used the procedure much more than any of his predecessors, Reid was not the first to fill the amendment tree. George Mitchell (D-ME) filled the amendment tree once as majority leader in 1993, and then again at the insistence of Robert Byrd (Smith, 2010). The next leader to fill the amendment tree was Trent Lott in the 105th and 106th Congress (in which he filled the tree twice and eight times, respectively). Lott’s successor, Bill Frist (R-TN) used the procedure in conjunction with cloture to prevent the consideration of any amendments aside from Frist’s amendments that he proposed given his right of first recognition (Smith, 2010). Frist went on to use the technique six more times (Smith, 2010). Given, however, the changing nature of the Senate and the move toward obstructionism, Reid was forced to use the procedure much more often than his predecessors.⁴

These parliamentary tactics obviously have their benefits. If the majority leader is able to invoke cloture and maintain unanimity within the caucus, then the majority leader is able to exert some agenda power. Indeed, Binder (1997) writes of the difference between the House and Senate,

Unlike the House—in which partisan majorities have been able to mold chamber rules to their liking—no such majoritarian character has taken root in the Senate. Control of the Senate agenda . . . has never been structured to reflect the interests of a partisan majority. (187)

However, by filling the amendment tree, the majority leader is able to, at the very least, exert negative agenda power, or the power to prevent policy from entering the legislative arena, and may even have the power to exert positive agenda power, or ensure the will of the majority is executed legislatively (Bargen, 2004; Campbell, Cox, & McCubbins, 2002; Chiou & Rothenberg, 2003; Gamm & Smith, 2002; Koger, 2003).

Still, this takes for granted a number of problems that arise from such agenda control. Unlike the House of Representatives, where members follow a logic in joining their party’s cartel in which supporting the party’s brand helps the representative’s electoral and legislative goals, senators are much less reliant on the party’s brand—especially those senators that come from states that are already hostile to that particular party (i.e., Joe Manchin in West Virginia). If the majority does indeed have agenda control and is intent on exercising it, then they risk cartelizing their caucus, and taking away a senator’s ability to distinguish herself from her party. Furthermore, it ensures that the party is able to pass its legislation—which for many, within the party, may prove to be more damaging than helpful.

Still, the intention of the majority leader, and by extension, the party is to protect their party as much as it is to push the party’s agenda. Moderate senators must consider their weak electoral circumstances before actively and visibly participating in the lawmaking process, more so than their counterparts (see Chaturved, 2017). By filling the amendment tree, the majority leader may actually be protecting the moderates of the party by offering them an excuse as to why they did not participate in the lawmaking process. Furthermore, he is also preventing amendments that would result in difficult votes for these moderates from proceeding toward a vote. In the following section, I discuss the logic behind senator’s voting decisions, and how filling the amendment tree could negatively affect the electoral outcomes of moderate senators and contribute to the polarization of the Senate.

Lawmaking, Voting Decisions, and Participating in the Senate

Lawmakers are often appraised on their voting records as a measure of their accomplishments, abilities, and overall ideology. However, focusing solely on a legislator’s voting record only provides a partial view of a senator’s legislative resume. Indeed, Hall (1996), in his work examining members of Congress, argues that legislators display their constituents’ preferences throughout the legislative game, not just in endgame voting decisions. Taking into account scholarship on lawmaking in the modern Senate, this would suggest that legislators should use some form of congressional participation as an effort to both symbolically and substantively affect the legislative process. With the Senate’s rules for amending bills fairly open, amending bills offers senators the opportunity to both shape the bill and express their position on the policy in question.

As mentioned in the previous sections, Senate rules allow for a fairly chaotic process to propose amendments. Lee (2009) notes that the process has grown in its chaos as minority party members, especially the leadership, have used the method to force vulnerable members of the majority into facing difficult votes. Still, Sinclair (1982, 1989) finds senators are more than willing to propose amendments to rework policy proposals directly on the floor.

In addition to electoral strategy, the use of proposing amendments in the modern era is expected. Floor amendments have utility beyond electoral strategy for the party, even at the individual level. Frances Lee (2009) argues that floor amendments serve three purposes for senators: they allow for individual senators to change pending legislation to fit their own preferences, they help senators shape the public’s perceptions on the senator’s performance and reputation, and they can be used for partisan electoral campaign purposes in which the minority party can critique the majority. As a result, senators could theoretically move the policy proposal to their ideal point in the policy space. They could also use it to signal their constituents that they are displeased with the legislation and are making an effort to either change the legislation, or include a provision that helps the senator’s state in return for support for the overall bill. If this is the case, then filling the amendment tree would indeed do damage to moderates, as a key tool to their reelection is taken away: their ability to move legislation or at least signal a desire to move legislation closer to their (and by extension, their constituents) ideal policy space.

However, if they are afraid of the political limelight, then they should offer few amendments, if any. Indeed, Chaturvedi (2017) in his analysis, of the Medicare Expansion Act of 2003 and the Affordable Care Act of 2009, finds that moderates offered, on average, fewer amendments to these bills and avoided taking clear positions on either bill in their floor speeches. Indeed, as Chaturvedi (2013, 2017) notes, moderate senators rely on increasingly volatile electoral coalitions in which they are often elected from states from opposing partisan allegiances (e.g., a Democrat from a “Red State” like Joe Manchin from West Virginia), or states with equal numbers of partisans (e.g., a senator from a “Swing State” like Mark Warner from Virginia).

Still, to run the chamber with this sort of agenda control would suggest that the majority party is not only able to push their own agenda, but that there is also homogeneity within the party in terms of party preferences. It may also suggest however that the Majority leader has rolled the preferences of deviant senators who are either unwilling or incapable of exerting their preferences on the chamber, as doing so would give the moderate senator unwanted attention. If moderates are from the volatile electoral constituencies mentioned above, then playing a pivotal role in the legislative game could do more damage than good—a reason to allow the majority party to roll the moderate.

Of course, this further polarizes the chamber as moderates become less ideologically moderate and more in line with the median party member. Furthermore, their voting record could also be brought into question. Although I argue earlier in this section that voting records do not account for the entirety of a legislative record, it is difficult to dismiss the importance of voting records vis-à-vis one’s reelection race. As mentioned, red state Democrats, blue state Republicans, and swing state senators need to be particularly savvy. They need to cultivate their own brand with their home constituencies that distinguishes them from the national party (Fenno, 1978). In the following section, I examine the amendment process in the era of the amendment tree and the effects it had on the majority and minority caucuses.

Data

To examine this in greater detail, I gathered the amendments proposed for every instance that Harry Reid filled the amendment tree during his time as majority leader during the Obama administration (from the 111th to the 113th Congresses). I choose these particular years because the assumption is that filling the amendment tree was done to protect key legislative proposals that would affect the party. Although Reid did fill the amendment tree prior to the Obama Administration, his use of the procedure was accelerated, presumably to capitalize on the Democratic control of the White House and Democratic majorities in the House and Senate in the 111th Congress, and the still rather large majority in the 112th and 113th Congress in the Senate. As such, I focus my attention on these three Congresses as the use of the procedure was unprecedented for these years.

To do this, I searched the congressional record using congress.gov for every piece of legislation considered during these Congresses. I then looked for legislation in which Reid employed the use of the filling the amendment tree procedure. I did this by looking for legislation in which Reid proposed amendments that changed the bill infinitesimally. His amendments, when used to fill the amendment tree, typically only changed the date that the bill was implemented. In those bills, in which this procedure was used, senators were, in most cases, blocked from proposing any amendments for consideration. The bills that met these criteria are listed in Appendix A.

Filling the amendment tree does not prevent senators from submitting amendments. Senators can submit amendments to be printed in the congressional record even if the chamber never considers the amendments. Typically, senators submitted amendments to afford their colleagues time to read and consider the amendments before actual floor consideration. The use of submitting amendments allows senators to submit amendments that they know will likely never be considered, creating a relatively costless form of participation. That is, they can propose amendments without having to go through the legwork of debating and defending them on the floor—a highly visible form of participation.

As a result, I tabulated the number of amendments submitted to legislation in which Reid filled the amendment tree. If senators are attempting to use amendments as a cue to their constituencies, then senators should submit amendments into the congressional record regardless of whether they are considered by the chamber as a whole or not. The total number of amendments submitted to bills in which the amendment tree was filled serves as the dependent variable. As the dependent variable is a count variable and the distribution is nonnormal, I use a negative binomial regression to predict the number of amendments proposed by a senator.⁵ I include every senator except Harry Reid, with the standard errors clustered by each individual senator, so as to not treat each senator as an individual observation if they were in more than one of the congresses examined.

The main variable of interest in this study is comparing moderates with their more ideological counterparts. As a result, I use Poole and Rosenthal’s DW-Nominate scores to measure ideology. However, as the consideration is moderates against ideologues, I take the absolute value of their calculated scores to create a measure from 0 to 1 indicating a moderate ideology (closer to 0) or a polarized ideology (closer to 1).

I control for party by running two separate models—one for Republicans and another for Democrats, as I am concerned with the effects of the procedure on both the minority and majority caucus, respectively.⁶ Within each model, I include a number of control variables. Considering that there is an electoral argument being made, I control for whether the senator in question is in the election cycle (i.e., up for reelection in the immediate election cycle following the congressional session). If senators are concerned about reelection, then they should use the amendment process strategically. Similarly, those retiring are no longer concerned with reelection and should care less about strategic participation. As a result, I include a dummy variable for senators who retired at the conclusion of the congressional session where a 1 corresponds to those who retired and a 0 corresponds to everyone else. I also construct a measure for how vulnerable a senator is using Cook’s political index. Negative scores reflect states in which the senator’s opposing party has an advantage. Finally, I include dummy variables for the 111th and 112th congresses to account for the differences in each congressional session.

To examine voting records, I calculated the number of times each senator voted with the Democratic majority on each of the bills, including procedural votes, in Appendix A. In the following section, I discuss the results of the models based on the data outlined here.

Results

A first, descriptive cut of the data seems to support the idea that moderates were no more likely to submit amendments when the amendment tree was filled than their counterparts or even during the Medicare expansion and affordable care act debates. Figure 1 illustrates the distribution of the number of amendments proposed by the senator’s ideological position, using the DW-Nominate scores.

Figure 1.

Total number of amendments submitted by ideological measure (DW-Nominate).

Moderates were less likely than both liberals and conservatives to propose an amendment on a bill in which the amendment tree was filled. We also see some evidence of positive control from the Democratic leadership as there are fewer amendments submitted to the congressional record from liberals than there are conservatives. This supports the notion that senators use the ability to submit amendments as a method to register their displeasure with both the legislation and the process. Interestingly, however, moderates who are not using the procedure to register their displeasure with the legislation or the process suggested that they are either okay with the substance of the legislation or that they are fully entrusting the party leadership.

Still, this is a descriptive cut of the data, and requires a more rigorous look. Table 1 summarizes the results of a negative binomial regression predicting the number of amendments submitted by Republicans when the amendment tree was filled.

Table 1.

Negative Binomial Regression Predicting the Number of Amendments Filed by Republicans on Bills With Amendment Trees.

	Coefficient	Robust SE
Distance from the Middle	1.93	.81
In Election Cycle	0.11	.22
Retiring	−0.57	.40
Swing State	−0.13	.45
Opposite State	0.24	.51
Bill Sponsor	−0.40	.61
Ranking Member	−1.29	.77
111th Congress	−0.08	.32
112th Congress	−0.40	.36
Constant	−0.94	.38
N = 1,126 (adjusted for 63 senators).

The results of the negative binomial regression largely confirm the descriptive results. The distance from the middle variable is significant at the .1 level and positive, suggesting that the further a senator sits from the ideological center of the chamber, the greater the number of amendments they submit. Figure 2 illustrates the change in predicted number of amendments by the ideological distance from the center. The most moderate Republican is predicted to submit less than one amendment whereas the most ideological Republican is predicted to submit nearly two amendments. Although the difference is only approximately one amendment, this suggests that moderate Republicans shied away from proposing and filing amendments all together, whereas their more ideological counterparts continued to participate. It is also interesting to note that regardless of what one could conjecture about Reid’s intentions behind filling the amendment tree, be it to protect the legislation, protect moderates, or stall the amendment process to negotiate, it did not stop ideological Republicans from filing amendments.

Figure 2.

Predicted number of amendments filed by ideology with 95% confidence intervals.

Despite the logic of using the amendment process to signal constituents, the variables measuring senators in the election cycle were not significant. Similarly, retiring senators and bill sponsors did not propose significantly more or less amendments. Vulnerability also had no impact on the number of amendments filed by Republican senators when the procedure in question was used. Returning to Lee’s (2009) logic behind why senators propose amendments, it seems here that the strategy behind the Republican use of the amendment process was to use it toward an electoral strategy in which they could use the content of the amendment against Democrats. Indeed, senators who filed the amendments knew there was little to no chance that their amendment would receive a vote.

Table 2 presents the negative binomial regression results predicting the number of amendments filed by Democrats on bills with amendment trees.

Table 2.

Negative Binomial Regression Predicting the Number of Amendments Filed by Democrats on Bills With Amendment Trees.

	Coefficient	Robust SE
Distance from the Middle	0.75	.81
In Election Cycle	0.05	.22
Retiring	−0.07	.40
Swing State	0.13	.45
Opposite State	0.07	.51
Bill Sponsor	−18.7	.61
Committee Chair	0.26	.77
111th Congress	1.52	.17
112th Congress	0.77	.18
Constant	−1.87	.38
N = 1,450 (adjusted for 76 senators).

Interestingly, the ideological measure did not have a statistically significant impact on the number of amendments filed by Democratic senators. This runs counter to the logic that Democratic senators, specifically moderate Democrats, were prevented from submitting amendments that would have helped with their reelection. The logic should be that if the amendment process was helpful to their reelection prospects, they should at the very least, follow their Republican colleagues and file amendments in protest, yet we see no such relationship.

Why then is there a difference in behavior? Part of the logic could be due to the costly nature of position taking, even through the filing of amendments. As Chaturvedi (2017) finds, moderate senators shy away from participatory actions like filing amendments and making floor speeches on highly visible or controversial legislation. As a result, it is conceivable that Reid filled the amendment tree on such legislation, and thus moderate Republicans shied away from filing amendments that could prove to be costly in a reelection race. Democrats, however, may have trusted Reid with the process, especially considering that he was using the process in an effort to protect them, and as a result, had not filed amendments. Indeed, Claire McCaskill (D-MO) noted with regard to Reid filling the amendment tree, “It’s not like we’re fighting Senator Reid. He’s trying to make the best of a very difficult situation” (Drucker, 2014).

Bill sponsors were predicted to propose fewer amendments than their colleagues as well. Intuitively this makes sense—if the amendment tree process is being implemented to protect the bill, the bill sponsor should be satisfied with the overall content of the bill and would thus find the need to file further amendments unnecessary.

So then what are we to make of the accusations that Reid’s filling the amendment tree hurt moderates? Indeed, the findings here suggest that Reid’s behavior did little to affect how Democratic moderates participate in the legislative game; Republican moderates, however, filed fewer amendments on legislation even in a costless situation in which they would not have to debate or defend their amendments. Similarly, there was no statistically significant relationship between ideology and the number of amendments filed by Democrats. Yet, this does not completely absolve Reid. Although moderates may have been unlikely to use the amendment process regardless of Reid, the use of filling the amendment tree does suggest some positive agenda control in the chamber. In exercising positive agenda control, the leadership then consolidates power and likely homogenizes voting behavior.

Figure 3 illustrates party unity scores from the 107th to the 113th Congresses. We should expect to see a clear divergence between moderates and their more ideologically driven counterparts, and for much of this time period, we do. However, there is a clear uptick starting at the 110th Congress for moderates.

Figure 3.

Party unity scores for the 107th to 113th Senates.

The implication becomes even clearer when looking at members in the majority against those in the minority. Figure 4 illustrates party unity scores from the 107th to the 113th Congresses by majority and minority status. Majority members of the Senate, including moderates, moved closer to party unity in the 110th to the 113th Congresses. Interestingly, moderate members of the minority diverged and were less united with their party in the same time period—further suggesting that the majority is able to exercise positive agenda control and is pushing the moderates in the chamber to vote with them.

Figure 4.

Party unity scores for the 107th to 113th Senates for majority and minority members.

Still, without examining just the votes on the bills in which Reid filled the amendment tree, it is difficult to draw the conclusion that filling the amendment tree truly homogenized the voting records of moderates. As a result, I now turn specifically to the voting records on bills in which the amendment tree procedure was used. Figure 5 illustrates the voting records of Democrats and Republicans by ideology in a Senate in which Democrats had 59 to 60 votes, and Republicans 40 to 41 votes for only the bills in which Reid filled the amendment tree. The voting record looks rather unremarkable from what we would expect. There is a sideways S shaped curve in which liberal Democrats were most loyal to their party and conservative Republicans were most loyal to their party with moderates falling somewhere in between.

Figure 5.

Voting records on amendment tree bills (111th).

However, as the Democratic majority shrinks, the voting record for the caucus becomes more homogenized. Indeed, Figures 6 and 7, illustrating the voting records of senators on bills in which the amendment tree was filled for the 112th and 113th Congresses, respectively, demonstrate a marked homogenized caucus in which the Democrats are clustered together at the 80% point in the 112th Congress and the 100% point in the 113th. Similarly, we see moderate Republicans breaking increasingly with their party in the 113th Congress.

Figure 6.

Voting records on amendment tree bills (112th).

Figure 7.

Voting records on amendment tree bills (113th).

Two-tailed t tests confirm these voting patterns on these specific bills as significantly different, as presented in Table 3. Although moderate Democrats (again coded as the 15 most moderate Democrats for the session) were significantly less loyal in the 111th Congress, they were much more homogenized and loyal in the 112th and 113th Congress. This is likely because there were fewer Democrats in the chamber, and thus the leadership could ill afford to lose many votes.

Table 3.

Differences in Voting Record for Moderate and Nonmoderates (Two-Tailed t Test).

	Democrats	Republicans
111th Congress
Nonmoderates	69.63	16.98
Moderates	61.31	39.07
Difference	8.32***	−22.1***
112th Congress
Nonmoderates	73.91	44.55
Moderates	70.74	49.89
Difference	3.17	−5.34*
113th Congress
Nonmoderates	97.81	26.56
Moderates	99.44	48.87
Difference	−1.63	−22.32***

p < .1. **p < .05. ***p < .01.

Moderate Republicans were affected by the procedure as well. In each Congress, moderate Republicans voted with the Democrats at higher rates than their ideological counterparts. Indeed, for the 111th and 113th Congresses, the difference is substantially higher at 22%.

Discussion

In this article, I have sought to shed light to the question of how Reid’s use of a little known parliamentary procedure affected the U.S. Senate and its members. The answer seems to be fairly nuanced. Based on the data presented here, some of the quotes at the front end of the article now seem much more rhetorical—Snowe’s remark that it was “shocking” that moderates could not get their amendments considered is less shocking given that a moderate Republican senator such as herself is less likely to even propose an amendment. Avoiding the legislative stage seems more important to these vulnerable senators than affecting legislation or even signaling constituents that they are different from their party.

Although moderates were unaffected in their efforts to affect legislation, filling the amendment tree did increase the majority leader’s power over the chamber, which in turn, increased his agenda control. This led to a more homogenized Senate majority caucus and a (even more) polarized Senate, opening moderates up to attacks of being too ideologically liberal or perhaps more accurately, more partisan, marching hand in hand with the Democratic leadership. As a result, it may be that Reid’s tactics complicated the electoral strategies for moderates.

Still, although the voting records of moderate senators certainly look more homogenized, it is difficult to predict what the voting records of moderates may have been if Reid had not filled the amendment tree. Had Reid not used the procedure, it is likely that a number of amendments that would be difficult for moderates to vote on may have gotten votes—but it is conceivable that moderate Democrats still would have voted them down, leading to a similar voting record.

Indeed, we should also temper the implications of this research as well in that it offers an empirical look at the effects of a Senate strategy based on available data. The argument could be made that Reid only used the procedure when moderates were sufficiently satisfied with the content of the legislation, either through explicit back room negotiations or implicitly based on the majority leader’s understanding of the senators’ constituency. More research using in-depth interviews with legislators and D.C. staffers would help address this issue.

Footnotes

Appendix A

List of Bills in Which the Amendment Tree Was Filled.

Congress	Bill No	Bill name
113	HR 3979	National Defense Authorization Act
113	HR 3547	Consolidated Appropriations Act
113	HR 3304	National Defense Authorization Act
113	HR 3204	Drug Quality and Security Act
113	HR 933	Consolidated and Further Continuing Appropriations Act
113	HR 83	Consolidated and Further Continuing Appropriations Act
113	S1086	Child Care and Development Block Grant Act
113	S815	Employment Nondiscrimination Act of 2013
112	HR 3606	Jumpstart Our Business Startups
112	HR 1	Disaster Relief Appropriations Act
112	S3187	Food and Drug Administration Safety
112	S2038	STOCK Act
112	S1619	Currency Exchange Rate Oversight Reform Act
112	S 990	PATRIOT Sunsets Extension Act
111	HR 5297	Small Business Jobs Act of 2010
111	HR 5281	Removal Clarification Act of 2010
111	HR 4853	Tax Relief, Unemployment Insurance Reauthorization
111	HR 4213	Unemployment Compensation Extension Act
111	HR 3590	Affordable Care Act
111	HR 3548	Worker, Homeownership, and Business Assistance Act
111	HR 3082	Continuing Appropriations
111	HR 2965	DADT
111	HR 1586	FAA Air Transportation Modernization Act
111	S1023	Travel Promotion Act of 2009
111	S22	Omnibus Public Land Management Act of 2009

Appendix B

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) received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Neilan S. Chaturvedi

Notes

Author Biography

Neilan S. Chaturvedi is an assistant professor of political science at the California State Polytechnic University, Pomona. His research focuses on American institutions, race and ethnicity, and elections. His research has been published in Legislative Studies Quarterly, Social Science Quarterly, Politics, Groups and Identities, the Journal of Asian American Studies, and Politics and Religion.

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