Mitt Romney--   95,669    (39.4%)    

Ron Paul--          55,455    (22.8%     

Jon Huntsman--  40,903    (16.8%     

Newt Gingrich            --  22,921    (9.4%      

Rick Santorum--  22,708   (9.3%       

Rick Perry--         1,709    (0.7%        

Others--                 3,583   (1.5%  

MANCHESTER, N.H. — Mitt Romney swept to victory in the New Hampshire primary on Tuesday, turning back a ferocious assault from rivals who sought to disqualify him in the eyes of conservatives, in a contest that failed to anoint a strong opponent to slow his march to the Republican nomination.

Mr. Romney, a former governor of Massachusetts, won by a double-digit margin, a validation of his strategy to use his neighboring state to cement his standing as the front-runner. The candidates who had hoped to use the primary to emerge as his leading rival fared poorly, leaving a fractured Republican opposition.

“Tonight we celebrate. Tomorrow we go back to work,” said Mr. Romney, who strode into his victory party at Southern New Hampshire University less than 30 minutes after the final polls closed to present himself as the candidate to beat for the Republican nomination.

Representative Ron Paul of Texas, whose candidacy has never concerned Mr. Romney, finished second. Former Gov. Jon M. Huntsman Jr. of Utah, who staked his entire campaign here, placed a distant third but pledged to fight on.

Mr. Paul, the only Republican candidate to rival Mr. Romney in the breadth of his organization across the country, congratulated Mr. Romney on his triumph and pledged to press forward with his campaign, declaring, “We have had a victory for the cause of liberty tonight.”

A week after winning the Iowa caucuses by just eight votes, Mr. Romney pieced together a coalition of moderate and conservative voters. The margin was more comfortable than commanding, but he will benefit handsomely by having five rivals still competing against one another to emerge as his main opponent as the race moves to South Carolina.

Mr. Romney, who struggled in the final hours of the campaign here to ward off attacks from rivals portraying him as an elitist who killed jobs during his high-flying days at a corporate takeover firm, delivered a pointed message to his fellow Republican candidates. He warned them not to play into President Obama’s hands by trying to destroy his candidacy.

“In the last few days, we have seen some desperate Republicans join forces with him,” Mr. Romney said. “This is such a mistake for our party and for our nation. This country already has a leader who divides us with the bitter politics of envy.”

His words were directed squarely at Newt Gingrich, the former House speaker, who accused Mr. Romney of presiding over the “looting” of companies. The attacks did not seem to help elevate Mr. Gingrich’s candidacy. He was locked in a close race for fourth place with former Senator Rick Santorum of Pennsylvania, who refrained from adding his voice to the attacks on Mr. Romney’s business background.

A prevailing sense among New Hampshire primary voters that Mr. Romney is the Republican candidate most likely to defeat Mr. Obama helped lift him to victory. He did well among those who consider the economy the most important issue, according to exit polls, and among Catholics and more affluent voters.

Mr. Romney moved to quickly set the tone of the night, accepting victory and delivering a speech with broad themes of the general election, well before the size of his winning margin was known. It was an attempt to take control of the race before confronting his biggest test in the first Southern primary.

“Tonight, we are asking the good people of South Carolina to join the citizens of New Hampshire and make 2012 the year he runs out of time,” Mr. Romney said, referring again and again to Mr. Obama, but not acknowledging any of his Republican opponents by name.

Mr. Romney intends to convey his muscle in the race on Wednesday by announcing his fund-raising figure from the final three months of last year, when he raised at least $23 million. He is set to roll out endorsements and advertisements during the 10-day spring toward the South Carolina primary, even as he begins his push for the Florida primary on Jan. 31.

The result of the New Hampshire primary left the rest of the field in such disarray — particularly given the poor showings of Mr. Huntsman and Mr. Santorum — that it was hard to see the day as anything short of a major victory for Mr. Romney. His aides have long made clear that they would welcome running against Mr. Paul, whose support is largely built around his libertarian views.

Mr. Huntsman, who logged more miles in New Hampshire than any other candidate, vowed to stay in the race. His advisers conceded that his bank account was dry and his path to victory was unclear, but he vowed to continue to South Carolina.

“Ladies and gentlemen, I think we’re in the hunt,” Mr. Huntsman said, speaking to his supporters in Manchester. “I’d say third place is a ticket to ride, ladies and gentlemen. Hello, South Carolina.”

Mr. Santorum and Mr. Gingrich delivered speeches at the same time on Tuesday evening, not conceding defeat, but arguing that the race was only beginning. They thanked the voters of New Hampshire before dashing off to South Carolina, where they hoped the electorate would be more welcoming to their message.