The Candidate Supply: How the Costs and Benefits of Running for Office Shape the Democratic Process

Dominant theories of U.S. elections focus on how candidates fluidly change positions based on the demands of voters. I argue instead that candidates' positions are more rigid. As a result, the supply of candidates, and not just the demands of voters, helps determine the ideological composition of the legislature. I describe a simple theory of the candidate supply, and I argue that when the costs of running for office are high, and/or the benefits of holding office are low, the supply of candidates will be more ideologically extreme. I then ground this theoretical argument empirically. First, using estimates of candidate positions based on campaign contributions, I show that candidates rarely change positions over time, and that incumbents do not change positions even when challenged by primary candidates with contrasting ideologies. Next, I validate the two key predictions of the theory. To investigate the varying costs of running for office, I compare state legislators who must give up their seat in order to run for the House to those who do not have to do so. Moderate state legislators are sensitive to this cost, while more extreme ones are not. To explore the expected benefits of holding office, I show how the candidate supply in one party becomes more ideologically extreme when the other party ``as-if" randomly takes office in a district. Having validated the theory, I then show descriptive evidence that the costs of running for the House have gone up over time, and the benefits down, thus helping to explain why polarization has risen in recent decades. Overall, the book points towards the importance of considering both the supply of candidates and the demands of voters, jointly, in order to understand the electoral process and the roots of polarization in our legislatures.Governmen