Spoilers? Evaluating the Logic Behind Partisan Disaffiliation Requirements for Independent and Third-Party Candidates

Abstract

In this article, we evaluate the rationale behind partisan disaffiliation laws, which prevent a candidate from running as an independent or from switching parties if they have not adequately severed their ties to an existing party. One prominent justification for these laws is that they help prevent voter confusion, which may result in the most preferred candidate losing. Utilizing a database of state legislative elections from 1968 to 2014, we categorize independent and third-party candidates into two groups: those who have run in the past as a Democrat or Republican, whom we refer to as former major-party candidates (FMPs), and those who have always run as a non-major party candidate (ANMs). The findings reveal that the latter appear less strategic about where to run, and they are unlikely to run again. In contrast, FMPs are much more likely to have held state legislative office and are more likely to have run multiple times; they are also more strategic, running under conditions that are advantageous for non-major party candidates. Voters react to this, giving ANMs far fewer votes than FMPs and being more apt to vote for them when “spoiling” an election is less likely. As a result, ANMs rarely deny winning candidates majorities, while FMPs who have won office in the past do so more than half the time. Our findings regarding “vote stealing” do not indicate a systematic tendency for FMPs to take substantially more votes from the party they recently left in comparison to the other major party. Overall, our findings indicate that partisan disaffiliation laws achieve the objectives they are designed to promote.