Wayne Allard Republican Mark Udall Democratic The 2008 United States Senate election in Colorado was held November 4, 2008.

Senator Wayne Allard decided to retire instead of seeking a third term.

The election featured an open contest because incumbent U.S.

Senator Wayne Allard declined to seek re-election.

He honored his 1996 pledge to serve no more than two terms in the U.S. Senate and announced that he would retire from his service to the US Senate and not seek a 3rd term, leaving Colorado's Class II Senate seat open.