Republican Rep. Joel Hefley, the dean of the Colorado congressional delegation, said Thursday he will not seek an 11th term this fall, setting up a wide-open race in the conservative 5th District anchored by Colorado Springs.

"This decision has not been easy to make," Hefley said. "I have received a great deal of encouragement to run again and I appreciate that support, but the timing seems right to move on to other opportunities."

Hefley, 70, said he wanted to remain in Congress until last year's round of base closures was completed; his district includes several military installations, including the sprawling Fort Carson Army post. His term as chairman of the Defense Committee of the NATO Parliamentary Assembly also ends in November.

Over the past year, Hefley publicly sparred with former Majority Leader Tom DeLay and led the House ethics committee when it rebuked the powerful Texas Republican. House leaders last year removed Hefley from his position.

"It's not that I didn't like the job or was anxious to get out. In fact, I'm looking forward to next year. It's with a great deal of mixed feelings that I do this," Hefley said.

Hefley also said he had job offers when he leaves Congress "that will prove there is life after politics," but he refused to be specific.

Hefley said he met with President Bush on Thursday to discuss the war in Iraq, but he did not tell the president about his retirement plans.

"The main thing I said to him is that we want to provide the resources needed to complete this job, but we need accountability," Hefley said. Hefley said Bush agreed.

Hefley said he got five or six calls from the White House urging him to run again and he felt bad about forcing the Republican Party to spend money defending a safe seat.

"There will be money drained off for a primary that wouldn't have to be otherwise. I hate that, but that's part of our process," he said.

Former El Paso County Sheriff John Anderson is the only declared Republican candidate, campaigning on defense because of the surrounding military bases, and cracking down on illegal immigrants.

Republican Party Chairman Bob Martinez predicted a strong fight in the Republican Party primary in August as Hefley's announcement clears the way for other candidates to jump in.

"He's been a stalwart in the Republican Party for many years. We know there is going to be a lively race for his seat," Martinez said.

Bob Loevy, a political science professor at Colorado College, said the race has the potential to be a free-for-all for Republicans since a win would almost guarantee a long-term career in the House.

The district has one of the country's biggest concentrations of veterans. It includes the Air Force Academy, two Air Force bases, a major Army installation and NORAD, the air defense command. The district has been represented by a Republican since the seat was created more than three decades ago.

"You can't underestimate the size of this prize," Loevy said. "Unless something very unusual happens and 2006 turns out to be a blockbuster Democratic year in the country, the Republican primary will determine who will sit in that seat."

Democrat Jay Fawcett, who served 20 years in the Air Force and fought in the 1991 Gulf War, is also running.

State Democratic Party chairwoman Pat Waak said Fawcett has a good chance of winning the seat because of his military background.

"The Republican regulars are sick and tired of the direction their party is going. The party has been taken over by the religious right," Waak said.

Ed Patru, spokesman for the National Republican Congressional Committee, said Democratic dreams don't come true in Colorado's 5th district.

"This is through and through a seat that is decidedly Republican. President Bush won this district by a 30-point margin," he said.

GOP Sen. Wayne Allard of Colorado said Hefley's loss will hurt Colorado.

"For two decades, he protected Fort Carson and Peterson Air Force Base, shepherding them safely through a time when several rounds of the Base Realignment and Closure (BRAC) process closed dozens of bases across the country," Allard said. "It speaks to his effectiveness that his district's major military installations remained intact."

With corruption scandals plaguing Republicans in the U.S. House and President Bush's approval ratings down, Republicans expect they will have to fight hard this year to keep control of Congress. Democrats need 15 seats to win control of the House.