OLYMPIA — State Sen. Bill Finkbeiner, a former Senate Republican leader who provided the crucial vote needed to pass a gay-rights bill earlier this year, will not run for re-election.

The surprise move, announced Thursday, puts the Eastside 45th District up for grabs. The district includes rural parts of King County as well as more urban areas such as Redmond and Kirkland.

"That's terrible, terrible news for the Republicans," said Chris Vance, a former chairman of the state Republican Party, who stepped down in January.

"Bill Finkbeiner ... demonstrated the ability to get elected over and over again by comfortable margins in a suburban district, and those are in short supply in the Republican Party right now," he said.

Republicans are now banking on Rep. Toby Nixon, R-Kirkland, to win Finkbeiner's seat. Nixon quickly announced Thursday that he is running for Finkbeiner's old job.

Finkbeiner, R-Kirkland, was elected to the state House in 1992 and to the Senate in 1994. He served as the Senate majority leader in 2004 when the Republicans controlled the Senate. Democrats regained control the next session. Finkbeiner resigned as the leader of his caucus late last year.

Finkbeiner said he is leaving the Legislature to spend more time with his family, and on other pursuits. He works as a property manager and is earning a master's degree in business administration at the University of Washington.

"I enjoy the people and the issues, but I've been doing it for 14 years and I'm at the point in my life where I'm getting a little older," said Finkbeiner, 36. "It's time for me to try something new."

Senate Majority Leader Lisa Brown, D-Spokane, said she is sorry to see Finkbeiner leave, but noted it creates an opportunity for Democrats to take his seat. Her party holds a 26-23 majority in the Senate. It wants to increase it this election.

"That's a district that Democrats have won and could win," Brown said. Democratic candidate Eric Oemig of Kirkland is already running for Finkbeiner's seat, she said, "and there may be another one."

District 45 is considered a swing district. Although 53 percent of the district voters went for GOP gubernatorial candidate Dino Rossi in the 2004 election, an equal proportion voted for Democratic presidential candidate John Kerry.

Senate Republican Leader Mike Hewitt, R-Walla Walla, said he is confident of retaining the seat, although he noted: "It's a defensive [election] cycle for us. There's no secret about it. My goal is to maintain everything I have this year."

Hewitt said he didn't try to talk Finkbeiner out of his decision. "When someone says their priority is their family, it's pretty self-serving to try and talk them into staying for other reasons," Hewitt said.

Nixon said that after Finkbeiner voted for House Bill 2661, which bans discrimination against gays and lesbians, people urged him to run against Finkbeiner in the Republican primary this year. Nixon said that he refused, but that he told people he would run if Finkbeiner decided to leave the Legislature.

Finkbeiner said his vote on the bill did not play into his decision to leave the Senate.

"I was really reinforced that I did the right thing after talking to folks since I took that vote. I got a lot more positive feedback than I got negative," he said. "It was a vote I feel good about."

Democrats spent almost 30 years pushing the gay-rights measure but were repeatedly blocked by Senate Republicans. Finkbeiner's decision this year to back the measure gave Democrats the cushion they needed to pass it into law.

Andrew Garber: 360-943-9882 or agarber@seattletimes.com