The 2008 United States Senate election in Colorado was held November 4, 2008 when Republican Senator Wayne Allard from Colorado's 4th district decided not to seek a third term and was succeeded by Mark Udall. .
Senator Wayne Allard decided to retire instead of seeking a third term. Incumbent Republican U.S. Democratic primary results Democratic nominee Mark Udall won the open seat, making this the first time a Democrat had held this seat since 1978. Member of the U.S. House of Representatives
from Colorado's 4th district 
