PORTSMOUTH, New Hampshire (Reuters) - A teary-eyed Hillary Clinton pushed for support on Monday as polls showed her poised for a huge New Hampshire loss to Democratic rival Barack Obama, but the former front-runner vowed to carry on with her presidential quest even if she loses.

Obama warned supporters against overconfidence as a flood of new polls gave him a double-digit lead over Clinton one day before the state casts the next votes in the race for the White House.

Polls will close in the state at 8 p.m. EST on Tuesday, with results expected to begin rolling in quickly.

At a campaign event in Portsmouth, Clinton choked up and grew uncharacteristically emotional when she talked about her reasons for seeking the presidency in the November election.

“Some of us put ourselves out there and do this,” she said, her voice breaking and her eyes glistening with tears, “against some pretty difficult odds and we do it, each one of us, because we care about our country.”

“But some of us are right and some of us are wrong,” she said in a quaking voice. “Some of us are ready and some of us are not.”

The incident resurrected memories of former Maine Sen. Edmund Muskie’s tears during the 1972 New Hampshire campaign, credited with helping to bring down his front-running bid.

Clinton, who would be the first woman president, promised to stay in the fight until it was over, possibly on “Super Tuesday” on February 5, when 22 states hold nominating contests in the fight to be the party’s nominee in November.

“Whatever happens tomorrow, we’re going on,” she told the CBS “Early Show.”

“I’ve always felt that this is going to be a very tough, hard-fought election, and I’m ready for that,” added Clinton, who finished third in the first contest in Iowa last week behind Obama and former North Carolina Sen. John Edwards.

Obama rolled across New Hampshire in an effort to turn out supporters, warning there was still plenty of work needed before Tuesday’s vote.

“Do not take this race for granted. I know we had a nice boost over the last couple of days but elections are funny things,” Obama, an Illinois senator vying to become the first black U.S. president, told supporters in Claremont.

In the state’s hard-fought Republican race, Sen. John McCain of Arizona held a more narrow lead over former Massachusetts Gov. Mitt Romney in new polls. He scrambled across the state to urge supporters to get out and vote -- and asked them to bring a friend.

Slideshow ( 22 images )

‘I’M GOING TO WIN’

“I need you to get out the vote tomorrow, this could be a very close election and it will depend on voter turnout,” McCain said in Keene. “I’m proud to say I’m going to win tomorrow.”

New Hampshire is the next battleground in the state-by-state process of picking Democratic and Republican candidates for November’s presidential election to succeed President George W. Bush.

Slideshow ( 22 images )

A Reuters/C-SPAN/Zogby poll showed Obama with a 10-point edge on Clinton in the state, 39 percent to 29 percent, as he gained a wave of momentum from his win in Iowa.

McCain was relegated to the political scrap heap last summer after sinking polls and poor fundraising forced him to shake up his staff and recalibrate his campaign, but he now leads Romney by 5 points in New Hampshire.

Clinton and Romney are both under pressure to revive their campaigns after disappointing showings in Iowa, and a second consecutive loss for either could be devastating.

Romney, who at one time led polls in Iowa and New Hampshire, finished second in Iowa to former Arkansas Gov. Mike Huckabee.

A wealthy former venture capitalist who has pumped tens of millions of his own money into the race, Romney said he was buoyed by a Sunday night debate where he tangled with McCain and Huckabee over their records on taxes and immigration.

“Right now it’s a neck-and-neck race. But with the debate last night and the support I received from that debate I anticipate winning tomorrow,” Romney said in Stratham.

Edwards, on a 36-hour campaign marathon around the state ahead of Tuesday’s vote, did not respond directly when asked by reporters about Clinton emotional response.

“I don’t have anything to say about that. I think what we need in a commander in chief is strength and resolve,” Edwards said. “Presidential campaigns are tough business, but being president of the United States is also a very tough business.”

The final day of campaigning in New Hampshire coincided with a bipartisan gathering of political moderates in Oklahoma attended by New York Mayor Michael Bloomberg, seen as a possible independent candidate for president.

But Bloomberg kept a low profile and repeated his frequent denials that he intended to be a candidate.

(Additional reporting by Steve Holland, Jeff Mason, Ed Stoddard, Jason Szep in New Hampshire; Jeff Franks in Oklahoma; Writing by John Whitesides; editing by David Wiessler)