In schools, churches and private homes, voters said their concerns were the economy, energy policy and federal spending. But the top worry was distrust of President Barack Obama and unease with the direction of the nation.
"I honestly am afraid for our country," said 59-year-old Linda Hatch, who attended her first precinct caucus Tuesday at Columbine High School in Littleton. She supported former Massachusetts Gov. Mitt Romney.
Hatch and her husband, Bill, live in a townhome because they can't sell a house they own in California. Bill Hatch said the last four years have been tough and that he feels a special urgency this year that Republicans get it right.
"This is more critical in the history of the nation than World War II, Columbine or 9/11," he said.
Fellow Republicans seemed to agree, though they were divided on which candidate to choose.
At the end of the day, it was former Pennsylvania Sen. Rick Santorum who claimed victory. Returns from all the precincts showed Santorum with 40 percent of the vote to 35 for Romney. Former House Speaker Newt Gingrich had 13, and Texas Rep. Ron Paul claimed 12 percent.
Cecilia Seipp of Wheat Ridge liked Santorum because "he's a Constitutional observer."
"He's a good Christian man," she said.
Santorum courted Colorado's evangelical conservatives heavily in recent days. He appeared at Colorado Christian University and made several stops near Colorado Springs, home of the Christian advocacy group Focus on the Family.
Romney also campaigned in Colorado and spent caucus night in Denver.
In the Denver suburb of Aurora, Colorado Republican Party Chair Ryan Call said he believed any of the remaining GOP presidential candidates could pose a serious challenge to President Barack Obama.
Veteran caucus-goers said there was a big uptick this year in campaigning. They talked about getting phone calls, emails and mailed pleas for support from the campaigns.
"They've all been calling. I can't even keep track anymore," Linda Hatch said.
But if the stakes were high, voters seemed confident the eventual winner would be able to defeat the president.
Said Longmont caucus-goer Cherie Turner, "I find it hard to believe our country would elect him again."
Former Colorado GOP chairman Dick Wadhams participated in the caucuses at Columbine High. He said the state GOP made a smart decision by moving its caucuses ahead a month. In 2008, Colorado's presidential caucuses were held on Super Tuesday, and bigger states stole the show.
"Last time we were really swallowed up. Now we're getting the attention," Wadhams said.
Associated Press writers Dan Elliott in Longmont, Ivan Moreno in Aurora and Thomas Peipert in Wheat Ridge contributed to this report.
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