DES MOINES, Iowa — The White House their goal, Republican presidential hopefuls raced across Iowa on Monday in final, full-day of frenzied appeals for support in precinct caucuses that open the 2012 campaign. "It is the race you make it," an upset-minded Rick Santorum told voters soon to pick a winner.
    Santorum drew large crowds as he hustled through five events; the six-person field had 23 combined. That and the
$13 million or more already spent on television commercials was evidence enough of the outsized importance Iowa holds in the race to pick a Republican opponent for President Barack Obama next fall.
    Campaigning like a front-runner, Mitt Romney had one eye on his GOP rivals and another on Obama as he argued he is in the best position of all to defeat the president. "The last three years have been a detour. They're not our
destiny," said the former Massachusetts governor, who is making his second try for the nomination and has been at or near the top of the Iowa polls since the campaign began.
    Texas Rep. Ron Paul flew into the state accompanied by his son, Kentucky Sen. Rand Paul, and urged supporters to "send a message tomorrow night that echoes not just around Iowa but ... around the world." Many in the audience of about 300 chanted "end the Fed," a reference to the Texan's pledge to abolish the nation's central bank as a first step toward repairing the economy.
    Most polls in recent days have put Romney and Paul atop the field in Iowa, with Santorum in third and gaining ground. More than a third of all potential caucus-goers say they could yet change their minds.
    "Do not settle for less than what America needs to transform this country. Moderate candidates who try to appeal to moderates end up losing," Santorum, the former Pennsylvania senator, said in a slap at Romney.
    Alone among the contenders, Newt Gingrich conceded defeat, at least in the first contest of the campaign.
    After absorbing a pounding in television commercials from Romney's deep-pocketed allies, the former House speaker said he was looking ahead to next week's primary in New Hampshire, and then to one in South Carolina on Jan. 21
    "I don't think I'm going to win, I think when you look at the numbers that volume of negativity has done its damage," he said of the Iowa caucuses.
    Romney is viewed as the overwhelming favorite in New Hampshire, although Santorum, Paul and Gingrich have all said they intend to campaign there.
    South Carolina figures to be more wide-open, the first contest in the South, and in a deeply Republican state.
    If others were thinking about conceding Iowa, they did not show it.
    Texas Gov. Rick Perry took swipes at Romney, Santorum and Paul in an appearance in Sioux City. "If you have my back tomorrow at the caucuses, I'll have your back for the next four years in Washington, D.C.," he said.
    Minnesota Rep. Michele Bachmann unveiled the first television ad in months. It hailed her as Iowa-born and the only "consistent conservative fighter" in the race and concluded, "She'll never back down."
    The commercial was the last in a race in which the candidates' own ads were sometimes overshadowed by the more negative ones run by super PACs, organizations established and funded by their allies.
    Perry and a super PAC supporting him spent the most, $5.5 million, according to one tally of the ad spending.
    But it was the combination of Romney ($1.3 million) and his super PAC ($2.7 million) that appeared to have the most noticeable impact on the race. That was particularly so in the final few weeks, when Gingrich surged to the front of the polls.
    The former speaker soon found himself under relentless attack in ads by the Romney super PAC. At the same time, the former Massachusetts governor's campaign took the high road, airing positive ads designed to show him in a favorable light.
    Short on funds, Gingrich was unable to respond in kind, declaring instead he would run only a positive campaign.
    It wasn't much of a contest, and before long, he faded, while Paul and then Santorum rose.
    In fact, Gingrich's emergence was only one in a series of twists that seemed to produce a new front-runner every few weeks.
    Bachmann earned that distinction when she won a straw poll last summer in Ames, but she was bumped off stride when Perry entered the race. His boomlet lasted until his first few debate performances were judged lacking, and then it became Herman Cain's turn. The former business executive suspended his campaign after being accused of personal indiscretions, and Gingrich began gaining ground, then Paul.
    Throughout it all, Romney remained steady, advantaged by his well-funded campaign, the super PAC that supports him and the missteps of his rivals.
    Yet to the end, the polls suggested the former Massachusetts governor was having trouble persuading Iowa Republicans that he was conservative enough to warrant their support.
    Somehow, even an intense post-Christmas push by the candidates through Iowa's cities, small towns and smaller towns left Iowa Republicans uncertain about which contender to back.
    "I'm really still undecided," said Bill Brauer, of Polk City, as he listened to Santorum speak on the campaign's final day.
    "I'm going to make up my mind tonight," he said.

    Associated Press writers Brian Bakst, Thomas Beaumont, Philip Elliott, Mike Glover, Kasie Hunt and Shannon McCaffrey in Iowa contributed to this report. Espo reported from Washington.