New research finds that a significant shift in candidate ideology results in only a modest 0.6 percentage point change in vote share, with stronger effects in high-profile races, high-information contexts, and competitive districts. The authors of the study conclude that the small electoral penalties for ideological extremism help explain persistent polarization in American politics, suggesting that turnout strategies may yield greater electoral benefits than candidate moderation.
Voter Response to Candidate Ideology
Researchers investigated how a candidate's ideological positioning influences their vote share in U.S. elections. Using a within-precinct design that isolated ideology's effects from turnout factors, the study aimed to measure the precise "persuasion effect" of candidate ideology across different electoral contexts. The central question was straightforward: How much do voters actually care about where candidates stand ideologically? By analyzing over 3.4 million precinct-cycle-contest observations with a composite measure of candidate ideology, the researchers sought to determine whether moderate positioning offers meaningful electoral advantages and whether these effects vary across different types of races and precincts.
Research Design and Data
The researchers employed a within-precinct analysis utilizing comprehensive election data from the MIT Election Data and Science Lab (2016-2022). This methodological approach allowed them to control for turnout effects and isolate the impact of candidate ideology on vote choice. They created a composite measure of candidate ideology by drawing from multiple sources, ensuring a robust assessment of candidates' political positions. By examining how vote shares changed when the ideological midpoint between candidates shifted, they could measure the pure "persuasion effect" of ideology. Their analysis spanned over 3.4 million precinct-cycle-contest observations, providing substantial statistical power to detect even modest effects across various electoral contexts.
Modest Impacts with Contextual Variations
The study revealed that ideological positioning has a statistically significant but surprisingly modest impact on election outcomes. A standard deviation shift in the ideological midpoint between candidates resulted in only a 0.6 percentage point change in vote share on average. However, this effect varied considerably across contexts. The impact was stronger in high-profile races like gubernatorial elections, when voters had more information, for incumbent candidates, and particularly in competitive precincts. By contrast, highly partisan precincts showed little to no response to candidate ideology. These findings help explain why polarization persists in American politics—the electoral penalty for extreme positions is simply too small to incentivize moderation.
Turnout Trumps Moderation
While the researchers didn't make explicit policy prescriptions, their findings offer valuable insights for political strategists and candidates. The modest electoral penalty for ideological extremism helps explain persistent polarization in American politics—candidates simply face limited incentives to moderate their positions. Most significantly, the authors suggest that "investing in broad-based voter registration and turnout efforts, as well as election reforms designed to ease access to the ballot, will likely generate greater electoral gains for parties than efforts focused on nominating moderate candidates." This conclusion challenges conventional wisdom about the electoral value of centrism and points to turnout strategies as potentially more impactful than ideological positioning for winning elections.
