MANCHESTER, N.H. — Mitt Romney was on the defense during Saturday's nationally televised New Hampshire GOP debate as his fellow Republican candidates jabbed him on his record repeatedly — at times seeming to all gang up on him at once.

Shortly thereafter, during a debate among the Democratic candidates, Sen. Hillary Rodham Clinton, the party's presidential front-runner no longer, took the same tack against campaign rival Barack Obama, accusing him of changing his positions on health care and "a number of issues" during a debate among the Democratic candidates.

"I have been entirely consistent in my position," countered Obama, adding that he and Clinton have a philosophical disagreement over her proposal to require Americans to purchase health insurance or face a penalty from the government.

The debates, sponsored by ABC and Facebook, were held one after the other. The candidates will debate again tonight on Fox News.

Romney's opponents seized on his so-called "flip-flopping" on key issues, a characteristic that experts have said irritates voters in New Hampshire more than his Mormon religion or sometimes-stiff personality, which seemed to have been the reasons for his second-place finish in Iowa Thursday.

But Romney, who got a little flustered during the debate, appeared unfazed afterward.

"I am happy to go to debates where all they talk about is me," Romney said at a rally of supporters after the debate, turning his attention to his win in the Wyoming GOP caucus, which also took place Saturday.

"The continuing personal barbs are interesting but unnecessary," Romney said during the debate.

Numerous experts have said Romney, the former Massachusetts governor who also headed the Salt Lake Winter Olympics in 2002, needs to win New Hampshire's first-in-the-nation primary on Tuesday to stay relevant in the race, but his top two opponents fixated on what they called the flip-flops.

"We disagree on a lot of issues, but I agree you are the candidate of change," Sen. John McCain, R-Ariz., said sarcastically, drawing a reaction from the audience.

Romney's campaign has emphasized a change and innovation theme since his official entrance in the presidential race in Michigan almost a year ago but has pushed it harder since the Iowa caucus.

During a discussion on immigration, McCain debated Romney over the definition of "amnesty," which Romney has said McCain's stance resembles.

"And for you to describe it as you do in the attack ads, my friend, you can spend your whole fortune on these attack ads, but it still won't be true," McCain said.

Kevin Madden, Romney's national press secretary, said he thought McCain "fell flat in whatever point he was trying to make."