Republican presidential hopeful and former U.S. Sen. Rick Santorum walks on stage before addressing a crowd at the Stoney Creek Inn on January 3, 2012 in Johnston, Iowa. Santorum, who was polling in the single digits until recently, is expected to finish first or second in today's Iowa caucus. (Photo by Andrew Burton/Getty Images)
DES MOINES -- No surprise here: The Iowa caucuses Tuesday night were poised to boost the presidential ambitions of the trio of candidates who scored a close finish at the top - former Massachusetts governor Mitt Romney, former Pennsylvania senator Rick Santorum and Texas Rep. Ron Paul - and imperil those who pulled up the rear.
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Beyond the obvious winners and losers, however, the Hawkeye State contest carried less predictable lessons learned about the Republican candidates, the nation's political landscape and the future of the GOP.
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The nine months leading up to the caucuses have marked the most volatile campaign for a Republican presidential race since the advent of polling, Gallup reports. The lead changed seven times in 2011 among Romney, Texas Gov. Rick Perry, former CEO Herman Cain and former House speaker Newt Gingrich.
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"It's been a roller coaster, and everybody had a chance in the lead car," said Lee Miringoff, director of the Marist Institute for Public Opinion. In surveys of voters as they arrived at the caucuses, one in six said they decided which candidate to back only earlier in the day.
Which leads to a lesson.
• The race has been less about the Republican contenders and more about their Democratic opponent.
The loyalty of Republican voters hasn't been to a particular candidate - they've jumped from one to the next - but to their determination to choose the candidate with the best chance of denying President Obama a second term.
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"Any one of them will stop the dragging of the United States toward European socialism," said Steve Grubbs, who was Iowa state chairman for Cain until his campaign imploded.
The apocalyptic view of the nation's future under Obama helped make Romney a more acceptable choice even among some voters who rejected him four years ago as an uncertain conservative who had flip-flopped on abortion rights and other issues.
"Mitt Romney has gotten a share of evangelical support that you wouldn't have anticipated," said Doug Gross, who led Romney's 2008 Iowa campaign. "There's a tug of war between their heart and their head, and their head is winning."
Half of the caucusgoers who said defeating Obama was the most important factor determining their vote supported Romney.
His standing at the top of the field is testament to another lesson learned.
• The advent of "super PACs" has created a powerful tool and reduced the risks of going negative.
Romney's campaign spent $1.5 million on soft-focus ads in Iowa that showed farmers walking down rows of corn as he vowed to restore American greatness.
That's only about half of the $2.8 million that Restore Our Future spent on hard-edged ads on Romney's behalf, most of them hammering Gingrich.
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Restore Our Future couldn't have existed four years ago. In 2010, the Supreme Court ruled a new kind of political action committee could collect unlimited contributions from individuals and corporations. The groups are independent of campaigns, but Restore Our Future is run by former Romney aides.
Gingrich blames the ads - which showed, among other things, a video medley of him saying "I made a mistake" - with costing him a onetime lead in Iowa polls and making him finish a distant fourth. Nearly two-thirds of caucusgoers said advertising was a factor in their decision.
Other super PACS supported Perry, Gingrich and Santorum, but none spent as much.
"Campaigns are like football - you have to play offense and defense - and the one playing offense is the super PACs," said Republican strategist Alex Castellanos. "They take out the other guy... Different players, different coaches, but it's the same team."
Same goal, but the legal division protects the candidate from being blamed for the onslaught of negative ads.
"Before Citizens United, the tag of a negative ad said, 'I'm Joe Smith and I approved this ad,'" Iowa-based pollster J. Ann Selzer said. Now, "candidates can deny they had anything to do with those messages, and that helps the candidate appear to stay above the fray."
One more lesson stems from Paul's close third-place showing.
• The Republican Party faces a debate over America's role in the world.
Nearly four in 10 caucusgoers said they were participating for the first time, and most of them supported Paul. He drew an unusual number of independents - nearly one in four of those who attended - and won the votes of just over half of younger voters, those under 30.
Still, Paul's opposition to "entangling alliances" and foreign intervention has isolated him from the rest of the field and much of the Republican establishment. He calls for bringing all U.S. servicemembers home from Afghanistan, and he rejects the idea of U.S. military action against Iran's nuclear program.
"This fault line has run through this party for a long time, and it has flared up again," said David Yepsen, director of the Paul Simon Public Policy Institute at Southern Illinois University-Carbondale and a longtime analyst of Iowa politics. He likens Paul to Ross Perot, whose third-party bid in 1992 helped shape the national debate, increasing the focus on the deficit.
"American politicians are going to have to pay attention to what he is saying," Yepsen said. "The Ron Paul thing is real."