The Impact of Legislative Tenure and Seniority on General Election Success: Econometric Evidence from U.S. House Races

The last four election-cycles in the U.S. House of Representatives (2004–2010) witnessed two shifts in political party control of that legislative body—from the Republicans to the Democrats in 2006 and then back to the Republicans in 2010. Nevertheless, U.S. House incumbents of both parties running for re-election tended to enjoy a sizeable advantage over their general-election challengers during the period. The advantage is even greater for incumbents who are members of the leadership, key committees, or have lengthy tenure. Our results show that, ceteris paribus , membership in the House leadership is worth on average 6.8 percentage points towards the incumbent’s expected vote-share, and that membership in either of the two top committees is worth an additional 1.3 such percentage points. A ten-term incumbent can expect another 2.0 percentage points of vote share. Lastly, our results also indicate the existence of a wave effect favoring Democratic incumbents in 2006, and a slightly smaller wave effect favoring Republican incumbents in 2010.