Republican presidential hopeful Sen. John McCain, R-Ariz., walks Monday with CBS Evening News anchor Katie Couric in downtown Manchester, N.H.

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.

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

Clinton runs second in the surveys, with former Sen. 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 Illinois Legislature.

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.

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 Gov. 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.

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.”

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 backwards,” she said at a morning campaign stop, her tone changing and voice quavering.

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.

The ubiquitous polls suggested that independents would play a large role in determining the outcome of the Republican race. Political independents accounted for 41 percent of the vote in the 2000 Republican primary in the state.