The Texas lawmaker didn't say so, but the other campaign already built for a long campaign was Romney's. The former Massachusetts governor was closeted with aides and his family as he sweated out the caucus count in a state that humbled him four years ago.
This time, win or lose, he appeared destined to draw a smaller share of the vote than the 25.2 percent he did then.
Each of the three in the top tier strove to create a distinct identity and brought a different style to the race.
Santorum, the former Pennsylvania senator, ran the old-fashioned way, spending parts or all of 250 days campaigning in the state in hopes of emerging as the preferred conservative alternative to Romney.
Romney, the former Massachusetts governor, brought organization and money to the table, and was aided by deep-pocketed allies who ran television commercials attacking former House Speaker Newt Gingrich and others. That allowed Romney to take the high road in person, running as a former businessman who knew how to create jobs and defeat Obama.
Paul, the Texas congressman, was something of a blend of the two approaches, with money and organization. He drew on the support of younger caucus-goers with a libertarian-leaning approach that included a call to legalize marijuana and bring home U.S. troops from overseas.
Whichever among the three eventually finished ahead, it appeared likely the winner's share of the vote would be a record low for GOP caucuses in the state. Former Sen. Bob Dole had 26.3 percent support in 1996, when he won.
This time, the economy and the federal budget deficit were top issues, judged more important than abortion or health care, according to a survey of early caucus-goers.
Nearly a third of those surveyed said they most wanted a candidate who could defeat Obama, and those favored Romney as a group. Paul and Santorum split the votes of the one in four who called the selection of a true conservative their top priority, and the former Pennsylvania senator also made a strong showing among those who said their top priority was a candidate with a strong moral character as well as among late deciders.
Paul had an edge among younger and first-time caucus goers.
The survey by Edison Media Research for The Associated Press and television networks was based on interviews with 1,737 people arriving at 40 precinct caucuses across the state.
Obama was unopposed for the Democratic nomination. Even so, his re-election campaign set up eight offices across Iowa, made hundreds of thousands of calls to voters and arranged a video conference with caucus night supporters.
"This time out is going to be in some ways more important than the first time," the president told Democrats across the state. "Change is never easy."
The Iowa caucuses' outsized importance was underscored by the estimated $13 million in television advertising by the candidates and so-called super PACs as well as thousands of campaign stops designed to sway 100,000 or so voters.
Ironically, the weak economy that has made Obama appear vulnerable nationally was muted as an issue here. Despite areas of economic distress, the farm economy is strong. Iowa's unemployment in November was 5.7 percent, sixth lowest in the country and well below the national reading of 8.6 percent.
Despite its importance as the lead-off state, Iowa has a decidedly uneven record when it comes to predicting national winners. It sent Obama on his way in 2008, but eventual Republican nominee John McCain finished a distant fourth here to former Arkansas Gov. Mike Huckabee.
Even before Tuesday night's results were known, this year's Republican hopefuls were turning their attention to the next contests. Romney's campaign purchased time to run television ads in Florida, where balloting is three weeks distant, while Perry put down money in South Carolina.
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