The Rationality of Candidates who Challenge Incumbents in Congressional Elections

Making use of the numerous resources available to them, incumbent congressmen have come to enjoy very high rates of success in getting reelected. Typically, however, incumbents are challenged by relatively weak, unknown candidates, while potentially much stronger candidates are deterred. So why do these weak candidates engage in such apparently foolish behavior? Previous research has suggested several answers to this question. It is commonly argued that weak, inexperienced candidates either misperceive the odds against them, or that they are actually using a congressional campaign to pursue nonpolitical goals or political goals other than winning office. Others point out that weak candidates may be induced to run by a low probability of victory because their political opportunity costs are low or because a stronger than expected showing may serve as an investment in future campaigns. This paper argues, however, that there is a much simpler and direct reason why weak candidates choose to run against incumbents, and that is that they do so so as to maximize their probability of being elected to Congress.