MANCHESTER, N.H. -- Mitt Romney and John McCain sparred Sunday over their tax and spending records and who was a better agent for change, in the second Republican debate of the final weekend before the New Hampshire primary.

"You have a choice," Romney, the former governor of Massachusetts, said after ticking off his accomplishments in office. "You can select somebody who wants to fight for those things, or you can select somebody who's actually done those things."

McCain, a senator from Arizona, listed the pork-barrel spending he has exposed, as well as an Air Force tanker contract he squashed. "I think it was a reason why I wasn't elected Miss Congeniality in the Senate," McCain said. "I have a record of saving billions of dollars."

The race for the Republican nomination has gotten tighter ahead of Tuesday's voting. A new USA Today/Gallup Poll showed the lead for the Republican race within the margin of error in New Hampshire

McCain had the support of 34 percent of likely voters, up from 27 percent in mid-December. Romney was at 30 percent, down from 34 percent, and former Arkansas governor Mike Huckabee -- the Iowa caucus winner -- was third at 13 percent. Former New York City mayor Rudy Giuliani had 8 percent, while former Tennessee senator Fred Thompson was in the low single digits.

Republican presidential hopefuls participated in a Fox News Republican Candidate Forum Sunday in Manchester, N.H. From left were former New York City mayor Rudy Giuliani, former senator Fred Thompson, R-Tenn., former Arkansas governor Mike Huckabee, former Mass. governor Mitt Romney and Sen. John McCain, R-Ariz. (Charles Krupa ~ Associated Press)

Rep. Ron Paul of Texas -- who had 8 percent -- was excluded from the debate by the sponsor, Fox News Channel, and the New Hampshire Republican Party dropped out of the forum to protest the exclusion.

The stakes this week are especially high for both McCain and Romney.

Earlier Sunday, McCain declared, "I will win," while Romney hedged.

"I'm planning on winning in New Hampshire," the former governor said, but he added, "It may not happen."

Huckabee also downplayed his own prospects but said: "We're going to do better than expected."

Later, sitting elbow-to-elbow in a studio on the campus of St. Anselm College, Romney and McCain renewed a debate they have been conducting at long distance about who is better equipped to bring change to Washington.

Citing his record as a venture capitalist, Olympics CEO and governor, Romney said, "I've been in the economy. I've been in the real world."

McCain said: "I led the largest squadron in the U.S. Navy, not for profit but for patriotism."

Thompson jumped into the exchange, mocking Romney for saying the next president did not have to be a foreign policy expert so long as he was a good manager.

"My friend Mitt thinks expertise is important in all areas except national security," he said with a sly smile.

Thompson and Giuliani also scoffed at the notion that change should dominate the political debate -- as Thompson noted, just because Iowans said so in their caucuses last week.

Giuliani added, "Change is a slogan, and the examination has to be is it change for good or change for bad?"

Romney and Huckabee had several prickly exchanges.

At one point, Romney asked Huckabee a question as the former governor was responding to one posed by moderator Chris Wallace. Huckabee said he preferred to speak through the moderator.

Romney also prodded Huckabee about whether spending had increased during his decade as governor of Arkansas.

"You make up facts faster than you can talk sometimes," Romney said as Huckabee avoided giving a direct answer.

Huckabee said: "I had a court order that said we had to improve education."

Projecting confidence, McCain proclaimed in a TV interview: "I will win" the primary. Underscoring how much is at stake in New Hampshire, he added that victory is "vital" to his candidacy.

Later on his campaign bus, McCain qualified his prediction of a New Hampshire victory. "I believe I will win, but a lot of things can happen between now and Tuesday when the polls close," McCain said, adding that many New Hampshire Republicans still haven't decided whom to support.

Huckabee spoke of "a brotherhood" of sorts with McCain, fueled by Romney's criticism.

"We have both been brutally assaulted by Governor Romney with amazingly misleading ads that attacked and distorted and misrepresented our records, Romney attacking me in Iowa, attacking him in New Hampshire," the former governor said.

At the same time, Huckabee, who has styled himself as a straight-shooting candidate, confronted his own string of inconsistencies, including recent ones on the troop increase strategy in Iraq, the Writers Guild Strike and gambling.

"People are going to go through and nitpick. And that's fine," he said. "But I'll tell you why we won Iowa. We won Iowa because people believed that there was a need for somebody who had clarity in his positions. And I've stuck by those positions."

He said he hasn't changed his positions on gun rights, life issues, family values and President Bush's tax cuts. He said he had made some verbal slips but "I think most of us do, especially if we talk as much as politicians do."