Updated

Former House Minority Whip Roy Blunt, R-Mo, will announce that he's running for the Senate in Missouri on Thursday, according to two sources with knowledge of the Congressman's decision.

Blunt will travel throughout the state tomorrow to launch his candidacy, beginning with an appearance at 9:30 a.m. at Harris-Stowe State University, a historically black college in St. Louis.

"Having the campaign kickoff in St. Louis is a recognition from the Blunt campaign that Republicans need to do better in suburban St. Louis to win the race," said one Missouri-based GOP operative.

Blunt, who is a household name in Missouri, will begin as the Republican front-runner for the nomination, and has the support of the GOP establishment back home. He has run statewide several times over the course of his career, winning two terms as secretary of state before losing a GOP primary for governor in 1992.

His son Matt Blunt served as the state's governor from 2005 to 2009, but opted not to run for reelection, after facing of low approval ratings back home.

But Blunt faces the prospect of a primary challenge from former state Treasurer Sarah Steelman.

Steelman, an outspoken critic of the GOP establishment, ran a reform-oriented campaign for governor last year, losing in the primary.

Democratic Secretary of State Robin Carnahan has already announced her candidacy, and is expected to easily win the Democratic nomination.