Wow. The Republicans’ chances of picking up John Kerry’s Senate seat just evaporated.

Scott Brown, who surprised the political world with his upset victory in the 2010 special election, announced Friday afternoon that he will not enter the special election to replace John F. Kerry.

Brown was the frontrunner in the Republican race by far, and recent polls gave him a double-digit lead over the likely Democratic candidates, Congressmen Ed Markey and Stephen Lynch.

Brown’s decision leaves the Republican Party scrambling to find a viable candidate for the June 25 election. To make the ballot, candidates must gather 10,000 certified signatures in four weeks.

The Boston Globe reported today that national Republicans had mounted a “full court press” to convince Brown to stay in the race.

His stated reasons for stepping aside: campaign fatigue in the face of running a third race in four years, and disaffection with the partisan atmosphere in Washington. As for his real reasons, I won’t hazard a guess and I don’t really care. Looks like the Dems will hold onto the seat.

Must be an especially bitter disappointment for national Republicans after their maneuverings over the Secretary of State nomination. They scotched Susan Rice, at least partly in hopes of clearing Kerry’s seat for another run by Scott Brown. And if it hadn’t been for Senator McDreamy’s short attention span, it probably would have worked.