Ideological and partisan biases in ratings of candidate quality in US House elections

Objective This article explores whether voters evaluate candidates' ideology, partisanship, and quality independently or exhibit behavior consistent with motivating reasoning, rating co-partisans and candidates ideologically similar to themselves as more competent. Methods Using a survey of voters and experts from 2010 U.S. House elections, I estimate a model predicting an individual's rating of incumbent candidate competence for office and challenger candidate competence for office. Results Individuals ideologically distant from a candidate rate the candidate as less competent, yet rate co-partisan candidates as more competent. For incumbents, opposing partisanship amplifies the negative effect of ideological distance on candidate quality ratings, and shared partisanship mitigates the negative effect of ideological distance. Conclusion Only incumbents rated as the most competent can overcome the ideological and partisan biases of voters. Consistent with theories of affective polarization, these results imply that polarization runs deeper than partisan or ideological differences-it is personal.