(CNN) - Ken Buck, the tea party-backed Colorado Republican who came up short in his 2010 bid to unseat Democratic Sen. Michael Bennet, has kept a low profile since that narrow one-point loss.
Buck is not endorsing a candidate in the presidential race before Tuesday's caucuses, though the campaigns of Mitt Romney and Rick Santorum both reached out.
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But Buck, now seeking a third term as Weld County District Attorney, did handicap Tuesday's caucuses in an interview with CNN.
His prediction: Romney wins with close to 50 percent of the vote, thanks to his support from the political establishment and a healthy Mormon turnout, while Santorum runs a strong second.
Romney took 60 percent of the Colorado vote in 2008, handily beating John McCain, but Buck doubts that the former Massachusetts governor will do better this year.
"I think Romneycare has him, and his changing positions on social issues and some other things hurt him," Buck said. "But I think he is still viewed as the most electable of the Republican candidates when it comes to a head to head with Obama. He won't be as popular with the other more conservative Republicans, but I think the Mormons will turn out in large numbers and support him."
He said Santorum has emerged as the main conservative alternative to Romney in Colorado, where only registered Republicans are allowed to participate in the caucuses.
The former Pennsylvania senator has campaigned aggressively in Colorado, which has a substantial and vibrant evangelical community, since he pulled out of the Florida primary fight last month.
"I think it's partly the evangelical push, but Santorum is a worker," Buck said. "He shows up, he hits a lot of the right places. He is somebody who is viewed as getting out there and meeting with a lot of people."
Newt Gingrich and Ron Paul are largely non-factors, he said.
Paul won only 8% of the Colorado vote in 2008, and though Gingrich is campaigning in Colorado on Monday, he has almost no operational presence in the state.
"I don't see much of a Gingrich influence here," Buck said. "I don't see any ground game for him. I don't see him on the air. It seems like he has decided to take a pass on Colorado."
