Turnout and presidential coattails in congressional elections

Estimating the impact of turnout on House election results is problematic because of endogeneity and omitted variable bias. The following study proposes an instrumental approach to correct for these problems by using a series of fixed effects two-stage least squares panel-data regression models covering three congressional apportionment cycles (1972–1980; 1982–1990; 1992–2000). The analysis tests whether voter participation decreases the House incumbent’s electoral support, regardless of the level of competition in the district. The study also aims to determine if an increase in participation benefits Democratic candidates and whether this effect is constant across apportionment cycles. The results show that the influence of turnout on incumbency vote share is conditional on the level of presidential support in the district. This finding is explained by the surge and decline thesis of Campbell (1960).