Nashua, N.H. ? Republican front-runner Mitt Romney stumbled down the homestretch of the New Hampshire primary on Monday, declaring, “I like being able to fire people who provide services to me” as his rivals intensified already fierce criticism.

“Gov. Romney enjoys firing people. I enjoy creating jobs,” said former Utah Gov. Jon Huntsman, who has staked his candidacy on a strong showing in today’s primary and has shown signs of gaining ground in recent polls.

Adding insult to any injury, Texas Gov. Rick Perry posted a ringtone to his campaign website that consisted of Romney saying, “I like being able to fire people,” over and over.

Romney is the odds-on favorite in New Hampshire, and Huntsman as well as other Republicans who are contesting the state have generally been content to vie for second place in hopes of emerging as his main rival in the South Carolina primary on Jan. 21.

“Second place would be a dream come true,” said former Pennsylvania Sen. Rick Santorum, as he raced through a final full New Hampshire campaign day that began before sunrise and stretched for more than 14 hours. The former Pennsylvania senator finished a surprising second in last week’s Iowa caucuses, but without money for television ads he has appeared to struggle as he seeks to convert that into momentum.

Romney, the former Massachusetts governor, won in Iowa by eight votes. A victory in New Hampshire would make him the first Republican in a contested presidential nomination battle to capture the first two races of the campaign since Iowa began leading off for the GOP in 1976.

The battle has grown increasingly rancorous in recent days — both in New Hampshire and next-up South Carolina — with Santorum, Perry and former House Speaker Newt Gingrich escalating their attacks on Romney’s claim that a background in business uniquely qualifies him to help create American jobs.

At the same time, an organization that backs Gingrich has spread the word that it intends to spend $3.4 million on television ads in South Carolina that are expected to attack Romney with gusto.

“Now we’ll see if he has the broad shoulders and can stand the heat,” said Gingrich.

Romney’s remark about firing people was the second jarring moment for the front-runner in less than 24 hours.

On Sunday afternoon, the millionaire businessman told an audience that he understood the fear of being laid off, adding, “there were a couple of times when I was worried I was going to get pink-slipped.” His aides refused to provide details.

On Monday morning, addressing the Nashua Chamber of Commerce, he said he wants individuals to be able to choose among different health insurance policies.

“That means the insurance company will have an 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. If someone doesn’t give me the good service I need, I’m going to go get somebody else to provide that service to me,” he added.

A few hours later, in a previously unscheduled appearance before reporters, Romney emphasized he had been talking about insurance companies.