Rep. Bob Beauprez (R) will not run for the open Colorado Senate seat and will announce his decision at a 3:30 p.m. press conference today at the Republican National Committee headquarters, according to several knowledgeable sources.

Beauprez was being heavily courted for the race by Gov. Bill Owens (R), who himself bowed out of the race to replace Sen. Ben Nighthorse Campbell (R) on Monday.

He could be seen chatting with Florida Rep. Katherine Harris (R) on the House floor just hours before his official announcement. Harris also passed on an open-seat Senate race earlier in the year.

Beauprez’s decision throws the Republican field wide open, with Reps. Scott McInnis and Tom Tancredo as well as former Rep. Bob Schaffer in the mix. Schaffer appears to be the furthest along in his thinking as he has already formed an exploratory committee to raise money for the race. A McInnis decision could come as early as tomorrow.

Other GOP names being mentioned include Lt. Gov. Jane Norton as well as state Treasurer Mike Coffman.

Colorado Democrats have coalesced behind state Attorney General Ken Salazar as their preferred candidate. Salazar announced his intentions Wednesday with the support of Rep. Mark Udall (D) and wealthy philanthropist Rutt Bridges (D), both of whom dropped out of the race to make way for Salazar.

Although only a freshman, Beauprez was seen as Republicans’ second strongest candidate, behind Owens, due to his exposure in the costly Denver market and his strong fundraising ability. He also is well liked by state and national party leaders for his stewardship of the Colorado Republican Party from 1999 to 2002.

House Republicans scored a major victory by keeping Beauprez in their ranks. His 2002 margin of victory was the narrowest of any House race in the country that cycle and many GOPers believe he is the only candidate capable of holding the 7th district for the party.

Republicans currently hold a 12-seat majority in the House.