[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2008/images/12/17/art.brownback.gi.jpg caption="Brownback will not run for re-election."] WASHINGTON (CNN) – Sen. Sam Brownback will announce Thursday he is retiring from the Senate when his term ends in 2010, allowing the Kansas Republican to explore a run for governor.
He will be the second GOP senator this year to publicly state he is leaving at the close of the 111th Congress.
Brownback, who unsuccessfully sought the 2008 GOP presidential nomination, will not reveal his future political plans during the three news conferences planned for Thursday in Kansas. But a source close to Brownback said he will file gubernatorial paperwork in January.
Under Kansas law, by waiting until next month Brownback will not have to disclose how much money he has raised until early January 2010. Brownback, a prominent figure in conservative circles, is expected to tap into a national fundraising base established during his years in the Senate as well as his failed presidential bid.
Brownback arrived in the Senate in 1996, winning a special election to fill the two remaining years of Senate Majority Leader Bob Dole’s term after the Kansas Republican resigned to focus on his presidential bid. Brownback, who pledged in that campaign to only serve two terms, went on to win re-election in 1998 and 2004. Philip Blumel, president of U.S. Term Limits, will join Brownback at the news conferences to thank him for abiding by “his pledge not to serve a third term in the U.S. Senate,” according to a news release from that organization.
Kansas Secretary of State Ron Thornburgh, a Republican, is currently raising money as he explores his own campaign for governor.
Several candidates are considered likely Senate successors for Brownback, including Kansas Gov. Kathleen Sebelius, a Democrat, as well as two House Republicans, Reps. Jerry Moran and Todd Tiahrt.
Brownback will join Florida Sen. Mel Martinez as the second Republican senator to announce his retirement following the 2008 elections. Texas Sen. Kay Bailey Hutchison is exploring her own 2010 gubernatorial bid; if she decides to run, it would create a third open Republican seat in 2010. Democrats, who gained at least eight Senate seats in the 2008 elections, only have to defend 15 seats in 2010, while Republicans have to protect 19.
Democrats currently hold a 58 to 41 seat edge over Republicans in the chamber with the Minnesota contest between GOP Sen. Norm Coleman and Democratic challenger Al Franken still unresolved.