Partisanship and Perceptions of Party-Line Voting in Congress

This paper explores public perceptions of congressional partisanship in an era of polarized parties. We use data from a module on the 2014 Cooperative Congressional Election Study (CCES) that asks respondents about the voting behavior of their legislators. Our results show that individuals underestimate the extent to which legislators from their own party vote the party line—even when primed with information about high levels of party-line voting in Congress—while fairly accurately perceiving levels of unity in the opposing party. We also find evidence that this perceptual gap endures, and at times widens, at higher levels of political knowledge and in the presence of elections. Finally, in a separate experiment, we explore how voters respond to differential levels of party-line voting by a hypothetical legislator. The combined results from the experiment and CCES module suggest voters’ perceptions often align with what allows them to have the most favorable impression of their party’s senators or unfavorable impression of the other party’s senators. The results suggest that biases in how voters process information about levels of partisanship in Congress may limit accountability in meaningful ways.