The battle among Mitt Romney’s competitors took center stage Saturday night, as the candidates toggled between swiping at the race’s frontrunner and launching personal attacks on one another at a critical New Hampshire debate.

Three days before the first-in-the-nation primary, the debate and its tone reflected the state of the polls. Romney is leading by a wide margin, and four other candidates appear to be in contention at least for second position.

Those candidates clashed frequently at Saturday’s debate – and most of those clashes involved Ron Paul, who is closest to Romney in the polls and wasn’t shy about reminding the crowd.

“Doing pretty well -- catching up on Mitt every single day,” Paul said halfway through the debate, summing up his campaign.

On everything from military service to federal spending, Paul went after his opponents and cast them as phony conservatives while his opponents accused the Texas congressman of stretching the truth to score political points.

A heated moment came when Paul, one of two candidates who served in the military, suggested Newt Gingrich sought deferments to avoid military service.

“I’m trying to stop the wars – at least I went when they called me up,” Paul said.

In response, Gingrich said he never asked for a deferment, but rather was married with a child and it “was never a question.”

“Dr. Paul has a long history of saying things that are inaccurate and false,” he said. “I personally resent the kind of comments and aspersions he routinely makes without accurate information and then just slurs people.”

Earning brief applause, Paul responded: “When I was drafted, I was married and had two kids, and I went.”

The exchange had little to do with the top issues in the campaign to date – such as the economy, the budget and Iran. But the personal nature of it was emblematic of a race that has taken on a sharper edge as candidates try to keep from being eliminated in the upcoming primary contests.

Romney won the Iowa caucuses by just eight votes, and he is poised to dominate in New Hampshire while leading in the polls in South Carolina.

Rick Santorum, who placed second in Iowa, is trying to build on that performance. Gingrich is trying to recover after sliding from the front of the pack. Paul has shown little hesitation about attacking either of those two candidates, while former Utah Gov. Jon Huntsman has built his entire campaign strategy around a strong performance in New Hampshire.

Santorum went after Romney early, dismissing the frontrunner as a mere manager.

“Business experience doesn’t necessarily match up with being commander in chief of this country,” he said. "Being a president is not a CEO. You've got to lead and inspire.”

He also said Romney’s tax plan is too meek to get the country's economy moving again.

Huntsman had a rare on-stage tangle with Romney at the very close of the debate on the issue of China, where Huntsman recently served as ambassador under President Obama.

After Huntsman criticized Romney for his tough talk on China and said the country needs a president who understands that relationship, Romney interjected.

“You were, the last two years, implementing the policies of this administration in China. The rest of us on this stage were doing our best to get Republicans elected across the country,” Romney said.

He went on to criticize China for “hacking into our computers” and manipulating their currency, among other offenses, and pledged to ensure they don’t “kill American jobs any longer.”

Huntsman gave his retort in Mandarin –- translated, he told Romney that he doesn’t understand the situation.

Gingrich also criticized Romney. He referred to published accounts in the media that described how some workers were laid off after Romney's investment company Bain Capital invested in their companies and sought to turn them around.

He said Romney should be judged on the basis of whether "on balance, were people better off or worse off by this style of management."

He criticized what he described as a “Wall Street model where you can flip companies … you can basically take all the money leaving behind the workers.”

Romney retorted that Bain Capital had created 100,000 jobs on balance, and that a businessman's experience was far better to fix the economy than a lifetime spent in Washington, D.C.

"I'm very proud of the fact that the two enterprises I led were successful," he said, referring to Bain and another firm.

The 90-minute encounter crackled with urgency.

Paul said Santorum was a "big government person" even though he campaigns as a conservative, referring to votes the former Pennsylvania senator cast to raise the debt limit.

Santorum answered that he had played a key role more than 15 years ago in legislation that overhauled the nation's welfare laws.

“You’re a big spender and that’s all there is to it,” Paul said. “To say you’re a conservative I think is a stretch but you’ve convinced a lot of people of it.”

Santorum responded: “You vote against everything. I don’t vote against everything.”

Rick Perry tried to get back into the debate. After his fifth place finish in Iowa, the Texas governor is polling in last place in New Hampshire. At the debate, Perry emphasized that he was an outsider “who is not corrupted by the process.”

There were few light moments, and even then one of the six presidential hopefuls on stage sought to turn the back-and-forth to his advantage.

At one point, Paul was interrupted by a bell meant to indicate his time to speak had expired. "There it goes again," he said.

Santorum replied instantly: "It knows you're not telling the truth."

The debate veered heavily at one point into social issues. Romney appeared to struggle on a question over whether the states should be allowed to ban contraceptives if they want. Romney described the scenario as “silly,” and said no states are pursuing such an option. “Contraception, it’s working just fine, just leave it alone,” he concluded.

Santorum stood by his positions on social issues. Asked what would happen if there were an amendment defining marriage as between a man and a woman, he said same-sex couples who currently are legally married “would not be married” anymore.

Gingrich suffered a flub on the debate’s final question -– on what the candidates would be doing on a Saturday night if they weren’t debating.

“I’d be watching the college championship basketball game,” he said.

After being corrected, he added: “I mean, football game.”

The ABC News debate at Saint Anselm College was the first in more than three weeks, and the first since Michele Bachmann dropped out of the race after a disappointing finish in Iowa this week. The candidates faced a quick turnaround for the second debate, set for Sunday morning in Concord.

The Associated Press contributed to this report.