Incumbency advantage

Incumbency advantage is the tendency of sitting officeholders to win reelection at higher rates than challengers. In U.S. House elections, incumbents who run again are reelected in the vast majority of cases, often more than nine in ten, and Senate incumbents also win often, though by smaller rates.

Researchers cite several reasons: greater name recognition and media coverage; constituent services and franking privileges; easier fundraising, including from PACs; a record to run on; and the ability to deter strong challengers. Safe districts drawn through gerrymandering and the sorting of voters by party also play a role. Some of the apparent advantage reflects the fact that popular officeholders tend to run again, and that districts lean toward the incumbent's party.

The size of the personal advantage appears to have declined in recent decades as voting has become more partisan, and national tides play a bigger role, as in a wave midterm election. Conservatives and others have championed term limits as a remedy, though supporters of experienced legislators argue term limits would shift power to staff and lobbyists. The Supreme Court held in U.S. Term Limits v. Thornton (1995) that states cannot impose term limits on members of Congress.