DENVER – Mitt Romney arrived in Denver on Tuesday ready for a victory party in the Colorado Republican caucuses. He left stunned, as Rick Santorum claimed victory.

Romney took the stage in front of a crowd of a few hundred supporters shortly before 10 p.m. and said the race was too close to call.

“I’m pretty confident we’ll come in No. 1 or No. 2,” Romney said.

The night belonged to Santorum, a former Pennsylvania senator, who also won the Minnesota caucus and a nonbinding primary in Missouri.

“This was a good night for Rick Santorum,” Romney said. “But I expect to become our nominee with your help.”

In Colorado, Newt Gingrich took third place and Ron Paul finished fourth.

Gingrich, who turned the race upside down with his Jan. 21 win in South Carolina, faded in Colorado and came in last in Minnesota. He was not on the ballot in Missouri.

In Colorado Santorum finished with 40 percent of the vote to Romney’s 35 percent, with 99 percent of the vote counted.

Minnesota was especially hard on Romney, who finished in third behind Paul.

Santorum addressed supporters in Missouri and said Tuesday’s results show what happens when Romney doesn’t outspend his rivals by a 5-to-1 margin in negative ads. As he did in Colorado throughout the last week, Santorum insisted that Romney is the wrong messenger for the GOP against President Barack Obama.

“I don’t stand here and claim to be the conservative alternative to Mitt Romney. I stand here and claim to be the conservative alternative to Barack Obama,” Santorum said.

Santorum fought hard for his showing in Colorado and invested more time here than any of the other three.

He made his first campaign appearance of the year last Tuesday, when Romney and Gingrich were still fighting out the Florida primary. Santorum made 11 personal appearances and advertised on television against Gingrich, who until last week, was seen as the most plausible alternative to Romney.

Santorum also ramped up his criticism of Romney, using his Colorado speeches to say the former Massachusetts governor cannot make the Republican case against Obama and the health-insurance mandate he passed in 2010.

Last week, he called Romney the “author and founder” of Obama’s health-care law, which drew heavily from the Massachusetts law that Romney signed.

Romney long ago wrapped up the support of Colorado’s Republican establishment, securing big-name endorsements from former Gov. Bill Owens and retired Sens. Hank Brown, Ben Nighthorse Campbell and Wayne Allard, plus state Speaker of the House Frank McNulty.

But Santorum picked up some key endorsements from the party’s right wing – notably former congressmen Tom Tancredo and Bob Schaffer and former Lt. Gov. Jane Norton.

In early returns, Santorum piled up wins in rural counties in both the mountains and plains. Romney took the ski country counties of Eagle and Vail.

Romney faltered compared with his own showing in 2008, when 59 percent of the state’s Republicans chose him over Arizona Sen. John McCain. But Romney dropped out of the 2008 race two days later in the face of McCain victories elsewhere in the country.

None of the candidates picked up delegates to count toward the 1,144 delegates the winner will need to become the Republican nominee at the party’s national convention in August. Colorado’s 36 delegates will be decided in April, at the GOP’s state and congressional district conventions.

On Tuesday night, caucus-goers elected delegates to county assemblies who pledged their vote to a presidential candidate. At the county meetings, they will compete to go to the later assemblies and try to get elected as delegates to the national convention in Tampa, Fla.

Colorado Democrats will hold their caucuses March 6.

jhanel@durangoherald.com