How does candidate ideology affect donors' contribution decisions in U.S. House elections? Studies of donor motivations have struggled with confounding of candidate, donor, and district characteristics in observational data and the difficulty of assessing trade-offs in surveys. We investigate how these factors affect contribution decisions using experimental vignettes administered to 7,000 verified midterm donors. While ideological congruence influences donors' likelihood of contributing to a candidate, district competitiveness and opponent extremity are equally important. Moreover, the response to ideology is asymmetric and heterogeneous: donors penalize more moderate candidates five times more heavily than more extreme candidates, with the most extreme donors exhibiting the greatest preference for candidates even more extreme than themselves. Republicans also exhibit a greater relative preference for extremism than Democrats, although partisan differences are smaller than differences by donor extremism. Our findings suggest that strategic considerations matter, and donors incentivize candidate extremism even more than previously thought.

Despite the longstanding underrepresentation of blacks in Congress, political science research has not settled on the cause. While there is increasing evidence that racial attitudes affect vote choice in today's congressional elections, how this effect interacts with the race of the candidates is unknown. This study addresses this debate by analyzing novel survey, census, and candidate data from the Obama era of congressional elections (2010–2016) to test whether racially prejudiced attitudes held by whites decrease their likelihood of supporting black Democratic candidates and Democratic candidates as a whole. In line with theoretical predictions, this paper finds that Democratic House candidates are less likely to receive votes among white voters with strong racial resentment toward blacks, and black Democratic candidates fare even worse. These findings help to explain the persistence of black legislative underrepresentation and contribute to theories of partisan racial realignment.

Though African-American and Latino electoral success in state legislative and congressional elections continues to occur almost entirely in majority-minority districts, minorities now have new opportunities in districts that are only 40–50% minority. This success can primarily be explained in terms of a curvilinear model that generates a “sweet spot” of maximum likelihood of minority candidate electoral success as a function of minority population share of the district and the proportion of the district that votes Republican. Past racial redistricting legal challenges often focused on cracking concentrated racial minorities to prevent the creation of majority-minority districts. Future lawsuits may also follow in the steps of recent successful court challenges against racially motivated packing that resulted in the reduction of minority population percentage in a previously majority-minority district in order to enhance minority opportunity in an adjacent non-majority-minority district.

This article develops a novel explanation for the incumbency advantage based on incumbents’ ability to signal positions that are ideologically distinct from those of their parties. Using voter-level data from the Cooperative Congressional Election Study and controlling for unobserved district heterogeneity, the study finds that voters in US House elections primarily use information about the ideology of candidates’ parties to infer the location of challengers, while they instead rely on information about the individual candidates’ ideologies to place incumbents. In higher-profile Senate elections, the difference between challengers and incumbents is trivial. Decomposing the incumbency advantage into valence and signaling components, the study finds that the signaling mechanism explains 14 per cent of the incumbency advantage in House elections, but only 5 per cent of the advantage in Senate contests. It also finds that a 50 per cent increase in party polarization increases the incumbency advantage by 3 percentage points.

US House incumbents enjoy profound electoral advantages, yet existing research has not asked whether individual voters actually prefer incumbents over newcomers, other things being equal. Instead, existing research has focused on showing that other things are not equal by emphasizing the structural advantages that incumbents enjoy. Political scientists, economists, and pundits have frequently speculated that voters either reward or punish incumbency, even when structural advantages are ignored. A randomized survey experiment administered in two waves to 1,976 respondents suggests that voters respond only minimally—if at all—to incumbency status once the structural advantages are held constant. Voters do not exhibit a strong general preference either for or against incumbency.