Manchester, New Hampshire (CNN) -- Hours before the first primary vote of 2012, Republican front-runner Mitt Romney tried to recover from a potential stumble Monday as his presidential rivals intensified their attacks against him.
Voters in New Hampshire's first-in-the-nation primary begin choosing their GOP candidates as early as 12 a.m. Tuesday in two small towns -- Dixville Notch and Hart's Location -- while polling stations in the rest of the state open at 6 a.m. and close as late as 8 p.m. ET.
The final day of campaigning saw Romney under fire for a comment about health insurance that quickly became fodder for criticism.
Asked about the issue in Nashua, New Hampshire, Romney said he wanted a person to be able to own his or her own policy "and perhaps keep it the rest of their life."
"That means the insurance company will have the incentive to keep you healthy. It also means if you don't like what they do, you can fire them," he said.
"I like being able to fire people who provide services to me," Romney added. "If someone doesn't give me the good service I need, I want to say I am going to get somebody else to provide that service to me."
Rival candidate Jon Huntsman immediately seized on the comment as an indication of Romney's political nature.
"It has become abundantly clear over the last couple of days what differentiates Gov. Romney and me," Huntsman said in Concord. "I will always put my country first. It seems that Gov. Romney believes in putting politics first. Gov. Romney enjoys firing people. I enjoy creating jobs."
The Democratic National Committee released a derisive Web video and called Romney "out of touch," while the campaign of Texas Gov. Rick Perry looped Romney's words to make a cell phone ring tone that quickly went viral.
Romney spent much of the rest of the day clarifying what he meant. At one point, Romney said he expected the comment to be taken out of context to try to hurt him, and his campaign issued a statement emphasizing he was talking about firing an insurance company, not people.
"Our opponents are taking Gov. Romney's comments completely out of context," said a statement by Gail Gitcho, the campaign's communications director. "Gov. Romney was talking about firing insurance companies if you don't like their service. That is something that most Americans agree with."
The latest twist in the GOP presidential race came on the eve of the first primary election a week after Romney won the Iowa caucuses by just eight votes over former Pennsylvania Sen. Rick Santorum.
With Romney in front in polls in New Hampshire and South Carolina, the site of the first Southern state primary on January 21, rivals stepped up their attacks by questioning the former Massachusetts governor's business background and electability.
In Manchester, former House speaker Newt Gingrich tore into Romney's record in the private sector at the helm of Bain Capital.
Though Romney has said his work at the Boston-based private equity firm ultimately led to the creation of 100,000 jobs, Gingrich said Romney's pursuit of wealth exacted a huge cost.
"What you have to raise questions about is, somebody goes out, invests a certain amount of money, say $30 million, takes out an amount, say $180 million -- six to one return -- and then the company goes bankrupt," Gingrich said. "Now, you have to ask a question: Is capitalism really about the ability of a handful of rich people to manipulate the lives of thousands of other people and walk off with the money? Or is that, in fact, a little bit of a flawed system? And so I do draw a distinction between looting a company, leaving behind broken families and broken neighbors, and leaving behind a factory that should be there."
Romney fired back that Gingrich and others were joining President Barack Obama in attacking the free enterprise system.
"As we'll find out, free enterprise will be on trial," Romney said. "I thought it was going to come from the president, from the Democrats, from the left, but instead it's coming from Speaker Gingrich and apparently others."
Gingrich had vowed earlier to run a positive campaign. But his tone has changed since his poll numbers plunged over the past month and he came in fourth in last Tuesday's Iowa caucuses.
"My conclusion after Iowa was very simple," he said Monday in Manchester in response to a question. "You could not engage in unilateral disarmament when 45% of all the ads being run were attacks on me. To do that would be to get out of the race."
In Derry, New Hampshire, Santorum predicted the Republican field will narrow to a showdown between himself and Romney, "and we'll win this race."
Responding to a reporter's question about his electability, Santorum said the country is more likely to elect a "strong conservative" than a man who has "run (previous elections) as a liberal, a moderate, and a conservative."
Santorum also cautioned voters to avoid the "establishment candidate."
"When we've run establishment candidates, we've lost," he said, referring to veteran candidates in past elections who he said were nominated because of a perception it was their due after long careers. "We lost with John McCain, we lost with Bob Dole. We lost with Gerry Ford."
Perry, meanwhile, made fun of Romney's comment over the weekend that he knows what it's like to worry about getting a pink slip, questioning whether such a wealthy man as Romney would fear losing a job.
Campaigning in South Carolina, the site of the next primary on January 21 and the first Southern state to weigh in, Perry said people there were out of work "because of what Mitt Romney and Bain Capital did."
Perry's decision to leave New Hampshire for South Carolina on Monday reflected his low poll numbers in the Granite State and hopes to revitalize his campaign in the traditionally conservative Palmetto State.
Another candidate, Texas Rep. Ron Paul, said he was holding back on big spending in another upcoming key primary state -- Florida.
Paul, who has consistently been among the top three in polling, told CNN that he would focus instead on caucuses that come after Florida's primary on January 31.
"We don't have a big campaign planned there, but they'll know we're there," Paul said in an interview.
Florida was penalized by the Republican National Committee for moving its primary earlier than rules allowed, with its 99 delegates cut down to 50. Still, Florida is a critically important state for the general election.
Asked about not focusing on Florida, Paul pointed out he had to prioritize spending his available campaign funding and had done well so far with a third-place finish in Iowa and polls showing him contending for second place behind Romney in New Hampshire.
"I think it tells you that we are realistic. That's the way we approached Iowa, we did pretty well there, and right now, polls are looking pretty good up here. So I think we're being realistic, we shouldn't be acting like the government and spend money we don't have," Paul said with a chuckle.
Paul's campaign chairman, Jesse Benton, said the focus after South Carolina will be the caucus states of Nevada, Louisiana, and Maine, which offer a total of 98 delegates, and where Paul's aides hope to rack up enough to keep their campaign going all the way to the Republican Convention in Tampa, Florida.
Paul also made clear that if he does better than expected here in New Hampshire and can raise more cash, his campaign might change course and compete more forcefully in Florida.
"We have to wait and see how things go," Paul said.
Huntsman, meanwhile, has made New Hampshire his make-or-break contest. He skipped campaigning in Iowa to spend all of his time stumping the Granite State, starting Monday in Lebanon in the north before working his way south to the coast.
A new poll Monday night by the American Research Group showed Huntsman's support rising, with 18% of respondents supporting him -- good for second place behind the 37% support for consistent front-runner Romney. Paul was third at 17% and Santorum fourth with 11%, followed by Gingrich at 10% and Perry at 1%.
The poll of likely New Hampshire primary voters had an error margin of 4%.
Romney and other GOP candidates also targeted Obama with sharp rhetoric Monday.
"I am very concerned that over the last three years you have seen, America, a very difficult time," Romney told an afternoon event in Hudson, New Hampshire. "This has not been a continuation of America's greatness from the past. I think it has been more of a detour than the destiny of America. I actually think the president has tried, but he has failed."
At a luncheon with business leaders in Greenville, South Carolina, Perry attacked the Obama administration for suing to block an immigration law recently enacted there, and he chided the National Labor Relations Board for intervening in the construction of a Boeing Dreamliner facility in Charleston.
"South Carolina, you are in a state of war with the federal government," Perry said.
In New Hampshire, the other candidates were busy. Gingrich had seven planned events Monday while Santorum scheduled six. However, Gingrich canceled his final event because of what his campaign said were security concerns over protesters at the entrance and exits.
Paul started Monday by greeting a crush of voters in Manchester.
"I wonder what the fire marshal would think," he said as he shook hands. "Let's keep it a secret."
Paul, who has the backing of many libertarians, predicted he will do well in New Hampshire because of his appeal among the 40% of Granite Staters who say they're independent voters.
"I think the people here in New Hampshire are very independent-minded, and I have a strong appeal because I have challenged both the Republican and Democratic Party leadership, and that means they want a message of cleaning house," Paul said in Meredith.
CNN's Paul Steinhauser, Peter Hamby, Dana Bash, Chris Welch, Rachel Streitfeld and Tom Cohen contributed to this report.