Rep. Jennifer Dunn (R-Wash.), the first woman to ever run for House Majority Leader, has decided to retire from Congress.

The six-term Congresswoman, who represents Washington’s 8th district, surprised supporters and party officials with her announcement Saturday.

“While I never took a pledge on term limits, I do believe that our nation is better served if from time to time we senior Members step aside to allow individuals with fresh ideas to challenge the status quo in Washington [D.C.],” she said in a letter to supporters. “It is time for me to move on. I will not seek re-election in November.”

Her decision throws the seat into play and gives Democrats a real opportunity for a pickup.

Democrats were already high on challenger Alex Alben, a retired high-tech executive, who reported raising $290,000, including $100,000 of his own money, in 2003.

But Dunn’s retirement could bring out other strong Democratic candidates as well.

Last year, when GOP officials tried to entice Dunn to take on Sen. Patty Murray (D) and thereby leave her House seat vacant, a long list of contenders emerged.

Among the top Democrats named were state Rep. Laura Ruderman, chairwoman of the House Democratic Caucus; state Rep. Ross Hunter, a millionaire former Microsoft executive; and Seattle TV newscaster Tony Ventrella.

On the Republican side, King County Councilman Rob McKenna and state Sen. Dino Rossi, chairman of the Senate Ways and Means Committee, were immediately listed as top Dunn replacements.

Dunn ultimately decided to seek re-election to the House, however, and none of the aforementioned entered the race, leaving Alben as the only announced candidate.

Back in D.C., Dunn’s retirement opens a seat on the exclusive Ways and Means Committee and leaves the Homeland Security Committee without a vice chairman.

Dunn previously served the Republican Conference as vice chairwoman, prompting her to challenge then-Majority Leader Dick Armey (R-Texas) for his leadership position in 1998. She came in third behind Armey and then-Rep. Steve Largent (R-Okla.) but became the first woman to seek that post.

“Jennifer Dunn is a pioneer for women in politics and she will be dearly missed,” National Republican Campaign Committee Chairman Tom Reynolds (N.Y.) said in a statement.

The 62-year-old divorced mother of two adult children, Dunn wed Keith Thomson in November in Bellevue, Wash., prompting speculation that her marriage was a key factor in her decision to retire.

“Her life has changed,” former Dunn political adviser and Bush administration official John Meyers told the Seattle Times. “Keith and she need to spend more time together. She has a new granddaughter. And, as she said tonight with grace and charm, ‘It’s time to move on,’” the paper quoted Meyers as saying.

Reynolds urged Washington state Republicans to get to work to find a replacement for Dunn.

“We hope the state party will quickly help find someone to try and fill the enormously large shoes Jennifer Dunn leaves behind,” he concluded.