Qualifies as a political stunner, the announcement Friday by Washington state Senator Bill Finkbeiner that he will not run for re-election this year.

The implications are large, but of a piece with developments already underway.

The surprise comes in part from the way Finkbeiner, a Republican who has voted conservative enough to become his party’s floor leader, seemed this year to tailor his legislative record to his district, on gay rights and other matters. His district, he seemed to suggest, was moving, was less and less conservative, and he had to respond. Usually you don’t do that if you’re planning to retire anyway.

Republican Representative Toby Nixon, plans to run for Finkbeiner’s seat, and Finkbeiner quickly endorsed him.

But the announcement was treated as a big deal – former state Republican Chair Chris Vance called it “That’s terrible, terrible news for the Republicans” – and there’s something to that view. You get a hint of it in Finkbeiner’s quote: “It’s always better to go out at the top of your game, and that’s where I am now.”

There’s some suggestion in that he was considering if a fall was coming. A decade ago, Finkbeiner’s 45th district, on the east side of King County, was solidly Republican – Democrats virtually need not apply. Finkbeiner himself was umopposed in 2002, and in 1998 he won over a Democrat with a solid 58.9%. But the all-GOP nature of the district has changed; in recent cycles its House delegation has been split between the parties, and Nixon had a close call in 2002. And other districts in the area have been shifting too, as indicated by the part switch of Republican Representative Rodney Tom – now a Democrat – last month.

Finkbeiner was a strong bet, though, to hold his Senate seat. Nixon, while well established in the district, has a tougher campaign ahead of him. The district could realistically go either way; it was close split in 2004 in the presidential race.

By the way, Finkbeiner is scheduled to be in Walla Walla on Monday to deliver Whitman College’s annual Matthew Shepard Lecture. Finkbeiner is a graduate of Whitman. He plans to speak on the topic, “In Search of a Philosophical Majority” at Maxey Auditorium.