The 2008 United States Senate election in Idaho was held on November 4, 2008. The primary elections were held on May 27. Incumbent Republican U.S. Senator Larry Craig decided to retire instead of seeking a fourth term. Republican Jim Risch won the open seat.
IncumbentLarry Craig announced his intent to resign following an incident where he solicited another man for gay sex in a public bathroom. Craig later decided not to resign; however, he announced that he would not seek re-election. The filing deadline for the election was March 21, 2008. A total of 13 candidates filed for the seat. Republican and Democratic candidates ran for their respective nominations in the May 27 primary.