Sen. Sam Brownback , R-Kansas, announced Thursday that he will not seek reelection when his term ends in 2010.

While not unexpected, Brownback’s decision creates the possibility of a competitive Senate race as several House Republicans and the current Democratic Gov. Kathleen Sebelius mull bids for the seat.

Brownback did not reveal his future plans, but is said to be considering a run for governor. Sebelius is term-limited and will leave the position in 2010.

His retirement fulfills a pledge he made in 1996 during his first Senate campaign that he would serve no more than two terms.

Brownback, a former evangelical Christian who is now a Catholic, first came to Washington in 1994, easily defeating Democratic candidate John Carlin, a former two-term governor, for the House seat representing Kansas’ 2nd congressional district.

Brownback declared for the Senate the day after Republican Majority Leader Bob Dole, the GOP presidential candidate, announced his resignation in June 1996. But GOP Gov. Bill Graves appointed Lt. Gov. Sheila Frahm, a moderate Republican, to fill the seat until a special election later that year.

Brownback beat Frahm in the special election primary by 13 percentage points, then took 54 percent of the vote in the general election against Democrat Jill Docking. He was easily re-elected in 1998 and 2004.

Brownback is ardently pro-life and says his religious beliefs inform everything he does. While in the Senate, Brownback co-authored a 2000 law banning human trafficking. He also has championed human rights around the globe and supports prisoner rehabilitation programs.

Brownback ran for the Republican presidential nomination in 2008, but dropped out before the Iowa caucuses when his campaign gained little traction in a crowded field.

If he does run for governor, Brownback might first face a primary; Kansas Secretary of State Ron Thornburgh also has expressed interest in the seat.

If he becomes the Republican nominee, Brownback would likely face Lt. Gov. Mark Parkinson. A former chair of the Kansas Republican party, Parkinson switched to the Democrats in 2006 to run on the ticket with Sebelius.

Prospective candidates already are positioning themselves for the race to succeed Brownback and the Republicans face the strong possibility of a competitive primary.

Rep. Jerry Moran , who just elected to a seventh term in the 1st Congressional District, has already filed papers with the Federal Election Commission to set up a Senate campaign fundraising committee.