On January 22, 2008, Governor Blunt unexpectedly announced that he would not seek re-election  because he had already "achieved virtually everything I set out to accomplish, and more ... Because I feel we have changed what I wanted to change in the first term, there is not the same sense of mission for a second."
A November 2007 poll conducted by SurveyUSA showed Blunt with a 44% approval rating. His approval among Republicans polled was 68%, but his rating among Democrats was only 23%.
On November 10, 2005, Democrat Jay Nixon filed the necessary paperwork with the Missouri Ethics Commission to launch a 2008 campaign for governor.
The gubernatorial and other statewide office primaries were held August 5, 2008.CQ Politics rated the race as 'Leans Democratic'.