Sen. John McCain claimed his second New Hampshire primary victory yesterday, defying convention and denying Mitt Romney a comeback in his back yard.

"Mac is Back! Mac is Back!" supporters chanted. But McCain won by never really leaving when his Republican rivals invested time in Iowa.

It leaves Romney scrambling for political survival, despite two second places and winning the Wyoming caucus. With his repeat primary gold, McCain cast himself as the Republican standard-bearer, a position he will have to defend Tuesday when Michigan holds its primary.

"Tonight we sure showed 'em what a comeback looks like," he said. At 71, he joked he's past the age to be called a Comeback Kid. "When the pundits declared us finished, I told them, 'I'm going to New Hampshire, where the voters don't let you make their decision for them.'"

With 78 percent of precincts tallied, he won 37 percent to 32 percent. Other Republicans were Mike Huckabee at 11 percent, Rudy Giuliani at 9 percent, Ron Paul at 8 percent, Fred Thompson at 1 percent, and Duncan Hunter with a few hundred votes.

Yesterday's win was as spectacular as his campaign's belly-flop last summer, when McCain was forced to shake up his campaign and crawl back into the race.

His victory speech pledged fiscal discipline, family values and national security. As chants of "USA! USA!" erupted, he said America would defeat terrorists. "In this great historic task, we will never surrender," he said. "They will."

In his concession, Romney referred to McCain as a Washington insider, saying his own business experience would enable him to fix problem-plagued Washington.

"I'll fight to be back here in November," he said as New Hampshire Sen. Judd Gregg, his national co-chairman, stood by his side.

Romney supporter Mike Doogue, a Manchester independent, blamed the loss on other candidates piling on criticism. He wonders how Romney can rebound. "As governor of Massachusetts, you'd think he would have some pull in New Hampshire," he said.

Romney voters complained McCain was too much of a media darling, but it was clear McCain maintained many of his supporters from 2000. Republican Susie Burdett of Bow was one of them. She settled on McCain again a year ago and never wavered in her support.

"He's the best man out there," she said, not far from "Straight-Talk" revelers munching on coconut shrimp and carved beef. "I didn't write him off at all. I knew we were coming back."

McCain stayed last night at the Crowne Plaza in Nashua, the same suite he slept in when he won in 2000. He flies this morning to Michigan and then to South Carolina, which holds its primary Jan. 19. Nevada also has a contest that day. The Florida primary is Jan. 29 and Super Tuesday is Feb. 5, when nominating contests are held in more than 20 states, including California and New York.

Romney looks to resurrect his presidential hopes in Michigan, where he grew up and where his father, George Romney, served as governor.

Donna Sytek, a former New Hampshire House speaker who serves as his campaign co-chair, said Romney is positioned to do well in other states. She said the troop surge in Iraq and McCain's past success in the state helped him.

"It's the triumph of momentum over organization," Sytek said. "Romney had organization and message. McCain was the sentimental favorite."

In victory, Sen. John McCain addresses supporters last night in Nashua. (AP)

Huckabee, a former Arkansas governor who won the Iowa GOP caucus five days ago, said he was encouraged by coming in third yesterday. The former Southern Baptist minister emphasized his evangelical roots in Iowa, but fashioned himself as a proven fiscal conservative in New Hampshire.

"Nobody thought we would be one of the contenders in New Hampshire," he said.

Giuliani captured a distant fourth, but he fares well in national polls. He plans to execute a national strategy to capture the GOP nomination. "Think of it as a kickoff in what will be a very long and a very tough game," Giuliani told supporters as he conceded the race.

Thompson left for South Carolina before the New Hampshire polls even closed for what may be his last stand. Paul, inspired by an enthusiastic Libertarian-leaning base, promised a long fight at his primary party in Concord. His supporters chanted a rotation of campaign slogans including, "Ron Paul Revolution; give us back our Constitution."

There was no hint of concession in Paul's lengthy speech.

"We always would like to do better, but we will continue this fight," said Paul, to hoots and cheers.

"We have to realize that hundreds and thousands -- or maybe hundreds of thousands -- have heard this message, and young people are getting excited. They've added it up and realize that freedom really works," Paul said.

Supporters said Paul's electability will not be an issue once his message gets out. "He did a great job on Leno last night," said Marie Banfield of Bedford, referring to Paul's appearance on "The Tonight Show" Monday.

"I'm tired of picking the lesser of two evils. Everyone else is the lesser of two evils. Ron Paul is someone I can feel good about voting for," Banfield said.

Romney's ads attacking McCain's positions on immigration and taxes may have backfired. While the candidates repeatedly spoke of their ability to effect change, the negative campaigning may have struck voters as the same-old politics, said Jennifer Borda, a professor of communication and an expert in political rhetoric at the University of New Hampshire.

"I think that a lot of voters have been turned off by that," Borda said last night. "I think it's been a detriment (to Romney)."

Sen. McCain toured the Union Leader on Tuesday morning, stirring memories of his visit on Primary Day 2000. Above, he and Publisher Joe McQuaid discuss a photo of Ronald Reagan with the paper's late publisher, Nackey Loeb. (DICK MORIN)

But Ovide Lamontagne, a Manchester attorney and senior adviser to Romney, said the New Hampshire Union Leader's endorsement of McCain and critique of Romney was a factor. He said Romney doesn't have to retool his message, he just needs to sharpen it.

"It's a two-man race -- Romney and whoever is the favorite son of the state they're in," Lamontagne said. "Romney will be a top-tier candidate in every state until Feb. 5. He's always going to be a contender. The question is where can he win and how many delegates can he pick up along the way."

Mike Dennehy, McCain's national political director, is optimistic about Michigan given recent polls there. He said the campaign has the money to compete through the Feb. 5 contests. And he pointed out after the 2000 victory in New Hampshire, the campaign raised $2 million in a single day.

"I think voters are telling us that they want someone with experience," Dennehy said. "They want someone who can be commander-in-chief on Day 1 -- no on-the-job training. I think we've proven today that we can go into someone's back yard and win."

Staff writers Michael Cousineau, Mark Hayward and Carol Robidoux contributed to this report.