Explaining Variation in the Degree of Electoral Competition in a Mature Democracy: U.S. Senate Elections, 1922-2004
44 Pages Posted: 13 Aug 2009 Last revised: 18 Aug 2009
Date Written: 2009
The degree of electoral competition varies across space and time in all democracies. We present a model that explains why and how variation in the competitiveness of U.S. Senate elections arises as a result of the interaction of constraints on the ideological positioning of candidates and differences within and across state electorates. Using this framework, we show that the factors that pull candidate platforms apart, including greater heterogeneity within an electorate, and primaries that restrict the electorate to registered party members, also lead to an increase in the number of contests that are highly competitive. Empirical implementation of the model using data from almost all Senate elections from 1922 to 2004 leads to predictions about where Senate races will be highly competitive, confirms the comparative static properties of the model, and generally provides robust support for this understanding of the roots of variability in the degree of electoral competition.
Keywords: degree of electoral competition, U.S. Senate elections, heterogeneity of electorates, primaries
JEL Classification: D70
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