United States Senate election in Oklahoma 2008 Tags: Election.The 2008 United States Senate election in Oklahoma was held on November 4 2008. The statewide primary election was held July 29 with the run-off on August 26. Incumbent Republican U.S. Senator James Inhofe won re-election to a third term. thumbnail start date 2008-11-04 title United States Senate election in Oklahoma 2008 Learn more... Loading...