The AP has called it, after several Colorado news outlets called it earlier in the day. Buck's loss is a loss
for the tea party, a loss for the Republican Party, and a loss for Colorado:
The victory gives Democrats a third crucial Senate win out West, including the reelections of Sens. Barbara Boxer (D-Calif.) and Majority Leader Harry Reid (D-Nev.). There is no final result in Washington state, where Sen. Patty Murray (D-Wash.) leads Republican Dino Rossi by one percent with less than two-thirds of the vote counted.
Republicans so far have gained six seats in the Senate. Democrats will hold a majority with either 52 or 53 seats.
Buck made some controversial statements during the campaign which may have cost him a few votes, but he was a bold voice in the West that promised to tackle government transparency and fiscal reform.