Republican presidential candidates argued over lack of experience, waterboarding and even the Super Bowl at St. Anselm College in Manchester, N.H., three days before the New Hampshire primary. Here are the key moments in less than three minutes. (Sarah Parnass/The Washington Post)

Republican presidential candidates argued over lack of experience, waterboarding and even the Super Bowl at St. Anselm College in Manchester, N.H., three days before the New Hampshire primary. Here are the key moments in less than three minutes. (Sarah Parnass/The Washington Post)

Marco Rubio came under withering assault in a debate here Saturday night as opponents for the Republican presidential nomination sought to cut down the senator from Florida over his relative inexperience and for abandoning his push for comprehensive immigration reform.

Donald Trump, the race’s national front-runner, also was put on the defensive by a newly invigorated Jeb Bush, who accused Trump of taking advantage of an elderly woman by using eminent-domain laws to take her Atlantic City, N.J., property as part of a casino development.

But it was Rubio, riding momentum after a surprisingly strong third-place finish in the Iowa caucuses, who became the top target in a rollicking ABC News debate that veered — sometimes chaotically — from Islamic State terrorists and North Korea to health care and immigration.

In an urgent bid to slow Rubio down ahead of Tuesday’s New Hampshire primary, New Jersey Gov. Chris Christie savaged the 44-year-old senator for never having made a “consequential decision,” lacking principled leadership on immigration and being unprepared for the presidency.

“I like Marco Rubio, and he’s a smart person and a good guy, but he simply does not have the experience to be president of the United States and make these decisions,” Christie said, reiterating points he has made all week on the campaign trail.

The candidate introductions at the ABC News GOP debate in New Hampshire did not go smoothly. (Phoebe Connelly,Gillian Brockell/The Washington Post)

Likening Rubio to President Obama, Christie added: “We’ve watched it happen, everybody. For the last seven years. The people of New Hampshire are smart. Do not make the same mistake again.”

Rubio appeared rattled by the assault, which came chiefly from Christie but was echoed by former Florida governor Bush. Rubio defended his Senate experience and suggested that Christie and other critics were discounting Obama’s skill in navigating Washington.

In one damaging exchange, Christie pounced on Rubio for repeating talking points within minutes — seeming to support Christie’s characterizations of Rubio as an overly scripted “boy in the bubble.”

“Let’s dispel with this fiction that Barack Obama doesn’t know what he’s doing,” Rubio said early in the debate. “He knows exactly what he’s doing. He is trying to change this country.”

Rubio repeated the same answer moments later — nearly verbatim, down to its cadence — leading Christie to mock him.

“There it is,” the governor said. “The memorized 25-second speech. There it is, everybody.”

Rubio repeated similar phrasing two more times more during the night.

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He also came under criticism for his position on abortion. Rubio opposes abortion without exception for rape and incest, something Bush said was an extreme position that would make him vulnerable in a general election.

Rubio’s retort: “I would rather lose an election than be on the wrong side of this issue.”

It was a difficult night for the freshman senator, who has shown himself in the previous seven debates to be an agile and prepared performer but had never faced such an onslaught from Christie and Bush. Both are desperate to revive their candidacies in New Hampshire or face the prospect of dropping out.

Trump, seeking to rebound in New Hampshire after a humbling Iowa second-place finish, returned to the debate stage after skipping the last event in Iowa because of a feud with the Fox News Channel. He ran into an uncharacteristically feisty Bush, who lashed out at him over the eminent-domain issue.

Asked by co-moderator David Muir whether he supported the use of eminent domain, Trump said that he did. “The Keystone Pipeline, without eminent domain, it wouldn’t go 10 feet, okay? You need eminent domain,” Trump said, adding that “without eminent domain, you don’t have roads, highways, schools, bridges or anything.”

But Bush interjected to call out Trump for blurring the differences between eminent domain for public and private use.

“What Donald Trump did was use eminent domain to try to take the property of an elderly woman on the strip in Atlantic City,” Bush charged. “That is not public purpose. That is downright wrong.”

From there, Trump and Bush shouted over each other. “He wants to be a tough guy tonight,” Trump said. Belittling Bush, Trump held his index finger over his lips and said, “Let me talk. Quiet.”

The audience booed Trump.

“That’s all of his donors and special interests out there,” Trump said, noting that many debate tickets go to party benefactors. “The reason they’re not loving me is, I don’t want their money. I’m going to do the right thing for the American public.”

Other candidates did not confront Trump as aggressively as Bush did. Sen. Ted Cruz of Texas, who has eviscerated Trump on the campaign trail, whiffed when Muir asked in the opening question whether he stood by an earlier comment that he thought Trump lacked the temperament to be commander in chief.

Trump pounced, suggesting America’s adversaries would shrink as Cruz had should they face a President Trump.

“If you noticed, he didn’t answer your question,” Trump said. “That’s what’s going to happen with our enemies and the people we compete against. We’re going to win with Trump.”

Ohio Gov. John Kasich — one of three governors clawing to get a ticket out of New Hampshire when the campaign moves next week to South Carolina and beyond — avoided confrontation with the other Republicans.

Instead, he sought to project a sunny disposition and talked about his record of cutting taxes and balancing the budget in his state. He also said conservatism should be defined by helping “people who live in the shadows.”

“If I get elected president, head out tomorrow and buy a seat belt, because there’s going to be so much happening in the first 100 days, it’s going to make your head spin,” Kasich said. “We’re going to move America forward. I promise you.”

The candidates reopened a polarizing debate over George W. Bush’s counterterrorism policies, particularly the former president’s authorization of waterboarding, which has been criticized as torture.

Trump defended his earlier vow that he would deploy the tactic to extract information from potential terrorists.

“Not since medieval times have people seen what’s going on,” Trump said. “I would bring back waterboarding, and I’d bring it back a hell of a lot worse than waterboarding.”

Other candidates who were asked about the matter said they would abide by congressional restrictions on the practice, while Cruz said he “would not bring it back in any sort of widespread use.”

Rubio embraced another Bush administration idea: opening the detention center used to house suspected foreign fighters at Guantanamo Bay, Cuba. Obama long has wanted to close the center, but Rubio said, “We should be putting people into Guantanamo, not emptying it out.”

Cruz also was asked to explain his statement that he would authorize “carpet bombing” as a way of attacking Islamic State terrorists, which some have criticized out of concern that such action would kill innocent civilians.

Cruz stood by his phraseology but said that he meant he would authorize the bombing of targeted roads and other facilities as well as what he called a university for terrorists. He then said that he would wait until freshmen matriculated.

Early in the debate, Cruz was led by Muir to apologize for what Ben Carson viewed as dirty tricks at the Iowa caucuses. Cruz’s campaign representatives suggested to caucus-goers that Carson was suspending his campaign minutes before the caucuses, which may have helped move some of Carson’s supporters to caucus for Cruz.

Cruz said he didn’t know about the matter at the time. Turning to face Carson, Cruz said: “When this transpired, I apologized to him then, and I do so now. Ben, I’m sorry.”

In the debate’s later, more substantive exchanges, Carson, a soft-spoken retired neurosurgeon, was largely absent. At one point, he remarked, “I’m not here just to add beauty to the stage.”

The candidates viewed Saturday night’s debate, held here on the small campus of Saint Anselm College that has quadrennially hosted presidential debates going back decades, as their most urgent of their eight debates so far.

A discussion about the heroin epidemic that is especially destructive in New Hampshire elicited a powerful, emotional moment for Cruz, as he talked about his sister, Miriam, who died from a drug overdose.

His voice cracking, Cruz described how she was addicted to painkillers, went to bed one night and never woke up.

“This is an absolute epidemic,” Cruz said. “We need leadership to solve it.”

David A. Fahrenthold in Goffstown, N.H., contributed to this report.