Abstract US Americans are divided along party lines, both in politics and personal relationships. While prior research shows a preference for dating co-partisans, it remains unclear why people prefer to date co-partisans and for whom the effects are strongest. Therefore, we examine whether perceived character quality of a potential partner, perceived similarity, and expected social approval mediate the effects of matching and non-matching political party on romantic interest and whether effects vary by gender and party combinations. We conducted an online dating experiment with US American partisans and partisan leaners aged 20–33 (N = 1,097). Respondents viewed six fictional dating profiles that randomly included ‘Democrat’, ‘Republican’, or no political information. Results show that romantic interest was largely driven by preference against out-partisans, rather than for co-partisans. Out-partisan rejection was driven by perceived similarity, followed by expected social approval and perceived character quality, while co-partisan preference was driven by perceived similarity and, to a lesser extent, perceived quality. The in-group preference was strongest for Republican men and women, while out-group rejection was strongest for Democratic women. Overall, our findings show that people use politics as a proxy for non-political characteristics. They also highlight the importance of distinguishing between in-party preference and out-party animosity.
Taflinger et al. (2026) studied this question.