Getting “Primaried” in the Senate: Primary Challengers and the Roll-Call Voting Behavior of Sitting senators

Abstract Primary challenges are semi-regular occurrences for incumbent members of Congress, and while many of these primary challengers never pose a serious threat to the incumbent, there are occasions when the incumbent faces a difficult primary challenge. How do incumbent members of Congress, particularly members of the Senate, act in response to primary challengers? This study examines the impact a primary challenger has on the voting behavior of incumbent senators to determine if incumbents change how they vote in Congress to counter their primary threat. In response to a primary challenger incumbent I find that senators shift their voting behavior and vote more often with their party’s leadership, but this is conditional on the threat-level posed by the primary challenger. High-quality primary challengers elicit the greatest shift in the incumbent’s behavior, according to this study. Supplemental data for this article is available online at https://doi.org/10.1080/07343469.2021.1922541 .