MANCHESTER, N.H. -- Her voice quavering, Sen. Hillary Rodham Clinton struggled Monday to avoid a highly damaging second straight defeat in the Democratic presidential race. Republicans John McCain and Mitt Romney scrapped for success on the eve of a New Hampshire primary that neither could afford to lose.

"You're the wave, and I'm riding it," Sen. Barack Obama, the new Democratic front-runner, told several hundred voters who cheered him in 40-degree weather after being turned away from an indoor rally filled to capacity.

Obama has been drawing large, boisterous crowds since he won the Iowa caucuses last week, and a spate of pre-primary polls showed him powering to a lead in New Hampshire, as well.

Clinton runs second in the surveys, with former senator John Edwards of North Carolina third, and the former first lady and her aides seemed to be bracing for another setback.

At one stop, she appeared to struggle with her emotions when asked how she copes with the grind of the campaign -- but her words still had bite. "Some of us are ready and some of us are not," she said in remarks aimed at Obama, less than four years removed from the state legislature.

Democratic presidential hopeful Sen. Hillary Rodham Clinton, D-N.Y., reacts as she takes the stage at a rally in Salem, N.H., Monday, Jan. 7, 2008. (AP Photo/Elise Amendola)

New Hampshire fairly crawled with candidates, so much so that at one point, McCain's three-bus caravan drove past Rep. Duncan Hunter of California, a long-shot Republican standing on a street corner with two other people waving to cars.

Republicans spar

Opinion polls made the Republican race a close one between McCain, the Arizona senator seeking to rebound from last summer's near collapse of his campaign, and Romney, the former governor from next-door Massachusetts.

After sparring over taxes and immigration in weekend debates with McCain and former Arkansas governor Mike Huckabee, Romney cast himself as the Republican best able to hold the White House. "I think Barack Obama would be able to do to John McCain exactly what he was able to do to the other senators who were running on the other side," Romney said as he sped his way through a half-dozen events on a final full day of campaigning.

Mindful of the polls, though, he declined to predict victory in a state where he had led in surveys for months.

Republican Presidential hopeful, former Arkansas Gov. Mike Huckabee speaks at a campaign stop in Mason, N.H., Monday, Jan. 7, 2008. (AP Photo/Alex Brandon)

McCain wasn't nearly as reluctant. "We're not gonna lose here," he boasted as he set out on a packed day of campaigning through seven cities. In a snow-draped setting in Keene, there seemed little doubt he had Romney in mind when he said voters would reject negative campaigning. "I don't care how many attack ads you buy on television," he said.

Romney has run several TV commercials against McCain in New Hampshire, arguing that the senator's immigration plan would offer amnesty for illegal immigrants and painting him as a disloyal Republican for twice opposing President Bush's tax cuts. McCain responded with an ad that includes a quote from The Concord Monitor that suggested Romney was a phony.

Clinton changes tactics

Obama won his Iowa victory on a promise of bringing change to Washington, trumping Clinton's stress on experience. She has struggled to find her footing in the days since, at the same time insisting she is in the race to stay.

Her husband, the former president, pointed out the obvious Sunday night in remarks before a college audience. "We can't be a new story," he said, speaking in something of a jocular tone. "I can't make her younger, taller, male."

Democratic presidential hopeful Sen. Barack Obama D-Ill., speaks at a rally Monday, Jan. 7, 2008, in Claremont, N.H. (AP Photo/M. Spencer Green)

Still, Sen. Clinton's aides have urged her to show more passion and emotion -- including laughter -- to give voters a sense of her warmer side.

By coincidence or not, she did so as she set out on a final day in New Hampshire.

"You know, I had so many opportunities from this country. I just don't want to see us fall backward," she said at a morning campaign stop, her tone changing and voice quavering.

"You know, this is very personal for me. It's not just political. It's not just public. I see what's happening. And we have to reverse it."

Edwards criticized Clinton as ill-suited to bring about change. "The candidate -- Democrat or Republican -- who's taken the most money from drug companies is not a Republican. It's a Democrat, and she's in this race tomorrow morning," he said.

Republican presidential hopeful Sen. John McCain, R-Ariz., smiles as he arrives at a campaign rally in downtown Manchester, N.H., Monday, Jan. 7, 2008. (AP Photo/Charles Dharapak)

Independents key group

The ubiquitous polls suggested that independents would play a large role in determining the outcome of the Republican race.

Men like Darren Garnick of Amherst, a registered independent, called himself politically "schizophrenic" as he crowded in to hear Huckabee speak. "I want someone to fix health care, and I want someone who will stand up to Iran."

Political independents accounted for 41 percent of the vote in the 2000 Republican primary in the state. McCain carried that group, 61 to 19, over George W. Bush, and won the primary even though Bush won the GOP nomination.

Now, eight years later, McCain hopes to attract enough independent voters once more to defeat Romney.

Republican presidential hopeful former Massachusetts Gov. Mitt Romney bows his head in prayer for the invocation at the Nashua Rotary Club Luncheon meeting at the Nashua Country club in Nashua, N.H., Monday, Jan. 7, 2008. (AP Photo/LM Otero)

But Obama's rise presents a challenge. Pre-primary polling in New Hampshire indicates he is poised to gain substantial backing there, as well.

That left McCain contesting Obama for independents and Romney for Republicans as he worked to climb back into the race after his campaign nearly imploded last summer.

Huckabee, the former Arkansas governor, flipped pancakes Monday and struck a tone that was both populist and conservative.

"There's a great need in this country to elect someone who reminds them of the guy they work with, not the guy who laid them off," he said in a pitch aimed at independent voters.

Speaking to conservatives, he added, "I have also heard folks say people in New Hampshire don't care about issues like family and the sanctity of life. I'd beg to differ."