AMES, Iowa — Mitt Romney's mathematical path to success in Tuesday's Iowa Republican caucuses seems simple: Just hold onto the 25 percent of the vote he got four years ago.
In 2008, that was enough only for a campaign-deflating second-place finish behind Mike Huckabee. This time, given the crowded field, it could be enough to win and give the former Massachusetts governor momentum that could become unstoppable.
The Romney camp smells opportunity — and as a result, its campaign suddenly has come alive in this state after being nearly invisible here all year.
"You can feel a growing energy in our campaign," said Romney's Iowa strategist, David Kochel.
But the campaign, which plans rallies around the state from Saturday through Tuesday, is also taking a risk. Should Romney stumble here again — such as by finishing a distant second, third or worse — fresh questions would come up about his electability. And should a rival surprise with a strong showing, that rival could become a serious threat in the states ahead.
Though polls show Romney at or near the lead in Iowa, perils lurk. Lots of voters, even those attending Romney rallies Thursday and Friday, still have not made a final choice. The powerful but politically fractured evangelical community could unite behind one candidate. Romney's Mormon religion is a concern in some quarters, as are his position changes on some issues dear to conservatives, such as abortion.
Romney nonetheless is counting on Iowa. He's buoyed by a corps of 2008 diehard supporters, who have waited for this moment.
"He's been so gracious, supporting Republican candidates, staying steady," said Karla Sexton, an Ames investment assistant.
Also helping Romney are voters who backed Arizona Sen. John McCain last time, the eventual nominee. He got 13 percent of the 2008 Iowa caucus vote in 2008.
Stewart Jackson, an Ames day laborer who's been out of full-time work for four years, said President Barack Obama "hasn't helped me at all." But Romney "understands a little bit more than most candidates what it means to develop jobs."
Charles Hurburgh, an Ames agricultural engineer, backed McCain. He thought Romney "went over the top last time, blitzing the state all the time. Iowans didn't take to that."
This time, Romney has been more subtle, using his network of volunteers to spread the word throughout 2011, and now sealing the deal with a last-minute tour of the state.
The biggest hurdle to success for Romney is his record as a center-right Republican who some conservatives say was too often on the wrong side of important issues. When running for statewide office in Massachusetts, he was sympathetic to abortion rights and gays serving openly in the military. But in recent years, he said he would not change the "don't ask, don't tell" policy on gays during a war, and he said he's firmly anti-abortion.
"I'm concerned how his opinions have changed over time," said Jane Alderman of Ankeny, who attended a Romney rally in West Des Moines on Friday.
Health care tops the wavering voters' list of qualms. As governor, Romney signed the 2006 Massachusetts law requiring nearly everyone in that state to obtain health coverage. It's widely considered a model for the 2010 federal health care law loathed by most Republicans.
"I think Romney has all the characteristics. The only thing holding me back is health insurance," said Bruce Halleland, who runs a Story City lumberyard.
Romney's insurance policy against an Iowa embarrassment is New Hampshire, which holds the nation's first presidential primary a week after the caucuses here.
"New Hampshire for us is the threshold," said Tom Rath, a veteran New Hampshire political strategist now advising Romney.
Romney campaigned in New Hampshire on Tuesday, returned Friday and stays there into Saturday. He's way ahead in polls there, but should an alternative come roaring out of Iowa with momentum, Romney's firewall could be badly damaged.
"A lot of New Hampshire voters are satisfied with Romney as their first choice," said Dante Scala, a political analyst at the University of New Hampshire.
But if former House Speaker Newt Gingrich, who has mainstream appeal, or Texas Gov. Rick Perry, who would have the money to challenge Romney across the country, were to do well in Iowa, Romney could face a threat, analysts say.
That looks unlikely, as both have faded in Iowa, but Romney wants to be sure. He needs New Hampshire even more now, because he's raised the stakes in Iowa, and what happens here now matters more to him.
"The best possible outcome (in Iowa) would be to do very little but win or finish second," said Dennis Goldford, professor of politics at Drake University in Des Moines.
But that strategy is now history, since Romney's campaigned here recently in earnest, and by doing so, he could be playing with political fire.
"The worst scenario," said Goldford, "is to be seen as going all out and not coming in at least a strong second."
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