In the 2004 Congressional elections, Daschle lost his seat to Republican challenger and former U.S. Representative John Thune in a bitterly contested battle. Thune prevailed by a narrow 50.6–49.4% margin, of 4,508 votes. Senate Majority Leader Bill Frist visited South Dakota to campaign for Thune, breaking an unwritten tradition that one party's leader in the Senate would not campaign directly for the other's defeat. Daschle's loss resulted in the first ousting of a majority or minority leader since 1952 when Arizona Senator Ernest McFarland lost his seat to Barry Goldwater. Daschle's Senate term expired on January 3, 2005.
