Mitt Romney said he is most fit to win the White House, but as the Iowa caucuses were to begin GOP rivals called him a status-quo hopeful lacking core beliefs. \"We\'re gonna win this thing with all of our passion and strength and do everything we can to get this campaign on the right track to go across the nation and to pick up other states and to get the ballots I need and the votes I need to become our nominee,\" Romney said in Marion, Iowa. The Romney campaign quickly said Romney meant the Republican nomination rather than Iowa. The former Massachusetts governor was neck-and-neck with libertarian-leaning Rep. Ron Paul of Texas and former Sen. Rick Santorum of Pennsylvania, who surged into a statistical three-way tie for first in a Public Policy Polling survey. The poll has Paul at 20 percent, Romney at 19 percent and Santorum at 18 percent, with a 2.7 percent margin of error. Rounding out the field are former House Speaker Newt Gingrich at 14 percent, Texas Gov. Rick Perry at 10 percent, Rep. Michele Bachmann of Minnesota at 8 percent and former Utah Gov. Jon Huntsman at 4 percent. At the same time, 41 percent of caucusgoers Tuesday are undecided, a Des Moines Register poll Saturday indicated. \"This is an election about jobs, about our economy, about the budget, scale of government, but it\'s about something more,\" Romney said in Dubuque Monday. \"It\'s also an election about the soul of America.\" He scheduled a rally in Des Moines Tuesday morning. Santorum told a packed coffee shop in Polk City Americans wanted a \"more consistent\" candidate than Romney. He challenged a Romney campaign premise that the former private-equity executive was best-equipped to revive the U.S. economy. \"We are not looking for a chief executive officer for this country,\" he said. \"We\'re looking for a commander in chief.\" Santorum\'s campaign planned a victory party Tuesday night in Johnston, near Des Moines. Paul assailed Romney and his other rivals as \"status quo\" agents and urged a crowd to caucus for him Tuesday as a way to defend personal liberty. \"As far as I\'m concerned, there\'s only one issue -- individual liberty,\" he said. Predicting he would finish strong Tuesday, Paul distilled his message into one line: \"The most important responsibility of government is to protect liberty and not to be the policeman of the world and not to have a runaway welfare state.\" He planned to appear at the Rock the Caucus assembly at a West Des Moines high school where young Iowans are encouraged to vote. Gingrich, leading in polls a few weeks ago, told reporters in Independence Monday he thought he would not win Tuesday. With so many negative ads aimed at him, it\'s \"a victory I am still standing,\" he said. He said Monday night he made an \"amateur mistake\" in saying those things. He told about 100 people in Davenport some supporters were irritated by the comment because it made it harder for them to get support for Gingrich Tuesday, The Des Moines Register reported. Gingrich scheduled a bus tour Tuesday. Perry, still hoping for a late surge, told voters Monday he had the stamina and the organization \"to finish this marathon,\" predicting voters in other states would turn to his candidacy even if he didn\'t do well in Iowa. He planned to hold two town-hall meetings with businesses Tuesday. Bachmann, another former favorite in polling, released an ad Monday with an announcer saying, \"Born and raised in Iowa, only one candidate has been a consistent conservative fighter, who fought \'Obamacare,\' who fought increasing our debt ceiling even as other Republicans were cutting deals with Obama.\" She also planned to appear at the Rock the Caucus assembly Tuesday. Huntsman, the only candidate not campaigning in Iowa, is staking his chances on a major showing in the New Hampshire primary in a week.