Florida Senator Marco Rubio came under fire from his rivals — and Donald Trump came under fire from the audience — in the last debate before the New Hampshire primary, as the do-or-die stakes spurred some of the fiercest clashes of the campaign so far.

The most endangered candidates made the most ferocious attacks. New Jersey Governor Chris Christie lit into Rubio as being weak and inexperienced. Former Florida Governor Jeb Bush landed some of his best punches against Trump over the use of an obscure legal maneuver in Atlantic City to turn the property of an elderly woman “into a limousine parking lot for his casinos.”

Trump drew boos from the audience when he defended the practice, known as eminent domain, saying it is needed for public projects and can be beneficial for the property owners.

“That’s all of his donors and special interests,” Trump said of Bush, over the crowd's outcries. “The reason they’re not loving me is I don’t want their money. I don’t need their money.”

Making War Decisions

The candidates also criticized President Barack Obama for his handling of the threat of the so-called Islamic state and terrorism.

Citing the brutality of the Islamic State, Trump said he would not hesitate to bring back waterboarding, the interrogation technique that critics say is torture.

"In the Middle East, we have people chopping the heads off Christians, we have people chopping the heads off many other people,” Trump said. “I would bring back waterboarding. I'd bring back a hell of a lot worse.”

Earlier, Christie accused Rubio of spouting a “memorized 25-second speech” over and over on the trail, but lacking the nuts-and-bolts experience to be commander-in-chief.

"You have not been involved in a consequential decision where had to be held accountable. You just simply haven't," Christie said, adding that Rubio has showed "truancy" in missing critical Senate votes.

Rubio shot back that Christie himself oversaw a state economy that was downgraded by debt-rating agencies nine times and didn't respond quickly enough to a major snowstorm in his state.

“Your state got hit by a massive snow storm. You didn't even go back. They had to shame you into going back," Rubio said.

Temperament Questions

Seven Republican presidential candidates, including recent debate no-show Trump and Texas Senator Ted Cruz, opened the debate with a clash over who would be the best commander-in-chief.

Trump said he has demonstrated the temperament building "a massive corporation’’ that others in the field lack.

"I’m not one with a trigger,’’ Trump said. "Other people up here believe me would be a lot faster.’’

Cruz said the question is “who can have the judgment when to engage and when not to engage. Both are incredibly important for a commander-in-chief. We need a president with the judgment and resolve to keep this country safe from radical Islamic terrorism.”

Immigration Duel

Rubio and Christie also sparred over Rubio’s support for immigration legislation in the Senate that he has largely abandoned.

"Here’s the bottom line. We can’t get that legislation passed,” Rubio said. “The American people will not do anything about people who are in the country illegally until the law is enforced and you can prove it to them."

Christie said Rubio failed to provide leadership on the issue.

“This is the difference between being a governor, who has to be responsible for problems, and not answering the question,” Christie said. “The question was, did he fight for his legislation. It's abundantly clear that he didn't.”

Cruz Vs. Carson

The debate turned quickly to charges and counter-charges that Cruz's campaign had misled voters in Iowa about news that Carson was taking a break from the campaign after Iowa. Carson did take some days off but stayed in the race for president.

Carson said that while he was not going to "savage the reputation of Senator Cruz,’’ he was disappointed that Cruz’s campaign attempted to mislead voters that he was dropping out of the race.

"It gives us a very good example of certain types of Washington ethics. Washington ethics basically says if it’s legal you do what you need to do to win,” Carson said. “That’s not my ethics. My ethics is you do what’s right.”

Cruz pointed out that Carson had said he was "taking a break’’ on a trip to Florida after the caucus. He said he called to apologize to Carson and that his campaign did not intend to mislead voters.

The Undecided

With as many as one-third of the state’s Republicans telling pollsters they’re undecided, the forum at Saint Anselm College in Manchester Saturday evening with seven candidates has the potential to sway the outcome of the first primary in the nation. 

“There’s a lot of uncertainty out there among Republican voters as to what to do and who to back,” said Dante Scala, a political science professor at the University of New Hampshire. “This could move a lot of votes, potentially.”

While Trump has a lead in New Hampshire of about 14 percentage points over Rubio in a RealClearPolitics average of recent polls, tonight’s encounter poses a risk if the former reality television show star doesn’t regain some of the swagger he lost in Iowa, said Kevin Madden, an adviser to Republican Mitt Romney’s 2012 presidential campaign.

“He kind of has to stop what looks like a slide,” Madden said. “He’s having to deal with the loser brand right now, and that’s not familiar territory for Trump.”

To make the stage, candidates had to place in the top six in national and New Hampshire polls or finish in the top three in Iowa. Fiorina appealed unsuccessfully to be included. Two other Republicans, former Pennsylvania Senator Rick Santorum and Kentucky Senator Rand Paul, suspended their campaigns after low finishes in Iowa.

Saturday’s debate is being moderated by ABC News anchors David Muir and Martha Raddatz. New Hampshire WMUR-TV anchor Josh McElveen and blogger Mary Katharine Ham also joined in the questioning.

John McCormick contributed.

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