An important implication of virtually every economic theory of political competition in a representative democracy is that the actions of elected political leaders are somewhat constrained by the desires of the electorate. Many of these theories suggest that even if politicians and their political parties would like to implement diametrically opposed policies, they would nonetheless be compelled to seek more moderate positions because to adopt extreme policies would risk being voted out of office. In this way, political competition is thought to bring opposing parties' positions closer to the "median voter". But to what extent is this notion empirically relevant for the political economy of the United States? Do voters implicitly moderate parties' positions? Can we quantify the extent to which they do or do not, and does it depend on characteristics of the voting populace, such as education levels? Providing credible answers to these questions is hindered by two fundamental problems: 1) it is difficult to measure the "closeness" of two opposing candidates' positions since only the policy decisions of the winner of the election is observed, and 2) a candidate's probability of winning an election - which depends on voters - may cause candidates to adopt certain positions; but those positions influence how voters vote, which in turn impacts the candidates' likelihood of winning the election, making it difficult to disentangle cause and effect from real-world data. Using data on the legislative voting patterns of members of the U.S. House of Representatives and election returns data, this project addresses these two problems by utilizing a quasi-experiment inherent in the U.S. electoral system. The approach of this project is to examine the roll call voting behavior of U.S. House members that were elected by a slim margin (say, by less than 1 percent). Under certain assumptions, this generates virtually random assignment of which party wins the Congressional District, among the elections that turned out to be close. The average roll call voting behavior of barely-elected Democratic Representatives should represent how the opponents of the barely-elected Republicans would have voted in roll call votes if they had not lost. This so-called "regression discontinuity design" strategy is also used to examine if Representatives respond to sharp changes in the probability of being re-elected - in other words, to assess whether or not the risk of not being elected compels politicians moderate their positions. The empirical analysis indicates very little evidence of strong or weak forms of this kind of responsiveness, suggesting that the diverging forces of partisanship seem to outweigh the converging forces of voters. The extent to which the political and electoral system in the U.S. operates to reflect the "will of the people" is of great concern to the public at large and motivates those who advocate political reform in areas ranging from campaign finance laws to term limits to the Congressional re-districting process. One way to evaluate how well the U.S. federal system functions is to assess whether or not voters, via the electoral process, compel partisan politicians and their parties to seek a "middle" ground, and moderate their policy choices. Indeed, much of the theoretical literature on this issue attempts to describe mechanisms by which voters can implicitly "discipline" politicians' decisions. However, the evidence on whether this notion is empirically relevant is far from conclusive, mostly due to the standard problem faced by social scientists, that of disentangling cause and effect in non-experimental settings. The findings of this research project can lead to two important advancements in our understanding of the operation of the U.S. political and electoral system: 1) a quantification of the relative importance of the convergent (the will of the electorate) and divergent (partisanship) forces that lead to public policy outcomes, and 2) a demonstration of how a "natural experiment" inherent in the electoral system can be used by researchers to learn about causal relationships in political and electoral contexts.
