Who Runs Against the Incumbent? Candidate Entry Decisions

Abstract This paper o¤ers an explanation for the common observation that political incumbents not only frequently win reelection, but often face weak competition or no competition at all when running for reelection. I explain this outcome by modeling the entry decision of potential election candidates as a process of self-selection. Candidates choose either to enter a political race against a known-quality incumbent or to wait for an open election. The model predicts that the entry decision is non-monotonic in candidate quality: Both low quality and very high quality candidates choose to enter the race. The tendency of midquality candidates to stay out increases the ex-ante probability that the incumbent will win, suggesting an explanation for incumbency advantage, the existence of uncontested races, and of "sacri…cial lambs.&quot