Topeka ? U.S. Sen. Sam Brownback, R-Kan., on Thursday said he would not seek re-election in 2010, but declined to address speculation that he plans to run for governor.

“I think we made it pretty clear in the announcement for this press conference, I wasn’t going to be talking about future plans. There will be plenty of time to talk about that in the future,” Brownback said.

Brownback, 52, said he was honoring a pledge he made to serve only two full six-year terms.

He acknowledged that his voluntary decision had a downside for Kansas since there are no term limits for Congress.

“It’s a seniority-based system,” he said of the Senate. “You do lose that seniority basis in stepping down. But for me, I would lose a lot more, and, I think, the people of Kansas would lose a lot more for breaking my word.”

Brownback was elected to the Senate in 1996 to fill the unexpired term of Sen. Bob Dole, who resigned to be the GOP nominee for president. Brownback then easily won full, six-year terms in 1998 and 2004.

Last year, Brownback ran unsuccessfully for the Republican presidential nomination, dropping out early in the race and supporting eventual nominee U.S. Sen. John McCain.

Brownback’s bid for Kansas governor has been widely anticipated. Democratic Gov. Kathleen Sebelius’ final term runs through 2010.

Brownback conducted a news conference in the Capitol with Philip Blumel, president of U.S. Term Limits, which advocates for term limits of elected officials.

Blumel praised Brownback for keeping his promise, which Brownback made in 1998. “This simple act of integrity is worthy of special note,” said Blumel, who noted that many politicians who signed a term-limit pledge have later broken that promise.

Brownback said he would spend his final two years in the Senate fighting for Kansas issues, such as funding for the $450 million National Bio and Agro-Defense Facility proposed for Manhattan, trying to secure an air tanker contract for Boeing, and preventing detainees from Guantanamo Bay from being moved to Fort Leavenworth.

He said he also wanted to help President-elect Barack Obama’s new administration, but that he opposed some of Obama’s proposals, which Brownback said looked like “spending your way into prosperity, that hadn’t worked in the past.”

U.S. Rep. Jerry Moran, R-Hays, who has said he is considering running for Brownback’s position, praised Brownback for his public service.

“The senator is someone who is unwavering in his beliefs and steadfast in his principles, including sticking to a term-limit pledge he made more than a decade ago to run for just two terms in the United States Senate,” Moran said.

U.S. Rep. Todd Tiahrt, R-Goddard, also is considering running for the Senate position.