The 1968 United States Senate election in Colorado took place on November 5, 1968. Incumbent Republican U.S. Senator Peter Dominick was re-elected to a second term in office over Democratic ex-Governor Stephen McNichols. Peter Dominick defeated Stephen McNichols in a landslide despite Richard Nixon, a fellow Republican to Peter Dominick, winning the state by a somewhat smaller margin over Hubert Humphrey in the concurrent presidential election.
This Senate seat would go on to vote Republican only once more since this election; in 1998, when former Democrat Ben Nighthorse Campbell won re-election in a landslide as a Republican.