The Legislative Success of “Giant Killers” in the U.S. House

In modern congressional elections, fewer than 10% of candidates who run against sitting members of Congress win and yet they comprise as much as 30% of the House in any given congress. In this paper, we examine the legislative effectiveness of those relatively rare challengers who knock off incumbents. We name them, “Giant Killers,” and find that during the early part of their House careers they are 43% more effective than those who first join the House by winning an open seat. We suspect that the coalition-building skills that a candidate needs to win a difficult race against an incumbent may be similar to and correlated with the coalition-building skills needed to be legislatively successful.