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 surveys gave him a double-digit lead over Clinton one day before the state primary.
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.
Voting ends in the state at 8 pm EST on Tuesday (0100 GMT on Wednesday), 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.
"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."
Clinton, a New York senator who would be the first woman U.S. president, promised to stay in the fight until it was over, possibly on "Super Tuesday" on February 5, when 22 states hold nominating contests.
"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, who spent the day rolling across New Hampshire in an effort to turn out supporters, warned 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.
Later, Obama told reporters he would not directly respond to Clinton getting choked up on the campaign trail.
"I don't know the context. I know this process is a grind and so that is not something I would care to comment on," he said in New London.
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.
'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."
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 rode 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, said he was the underdog but planned to spring a surprise. A third-place finish would not drive him out of the race, he told reporters.
"I am in this race through the convention and through the White House. I have no intention of stopping this fight that is the cause of my life," he said.
(Additional reporting by Steve Holland, Jeff Mason, Ed Stoddard, Jason Szep in New Hampshire; Jeff Franks in Oklahoma; Writing by John Whitesides; editing by Eric Beech)