MANCHESTER: Rising Republican presidential contender Marco Rubio came under heavy attack in a presidential debate on Saturday from rivals who accused him of being too inexperienced for the White House and walking away from an immigration reform plan he championed.

In a contentious debate three days ahead of Tuesday's New Hampshire primary, billionaire real estate mogul Donald Trump also battled with rival Jeb Bush over the use of eminent domain to seize private property and called for a compassionate approach to those who might lose their health insurance if Republicans repealed Obamacare.

Polls show Trump leading in New Hampshire, the second of the state-by-state nominating contests to select candidates in the Nov. 8 election, with Rubio coming fast after a surprisingly strong third-place finish on Monday in Iowa, behind U.S. Senator Ted Cruz and Trump.

New Jersey Governor Chris Christie and former Florida Governor Jeb Bush, who are vying with Rubio for support from establishment Republicans in New Hampshire, compared Rubio's experience in the Senate to that of President Barack Obama, who also was a first-term senator when he was elected.

"He simply does not have the experience to be president of the United States and make these decisions," Christie said of Rubio. "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 said he had shown in the Senate that he could get things done, and questioned Christie’s record.

"I think the experience is not just what you did but how it worked out. Under Chris Christie’s governorship of New Jersey, they’ve been downgraded nine times in their credit rating,” he said.

Christie accused Rubio of resorting to "a memorized 30-second speech."

Bush noted that by electing Obama, the country got "soaring eloquence" but few results.

Christie also led the charge against Rubio on immigration, criticizing him for backing a comprehensive reform bill in the Senate but then abandoning it when it foundered in the House under heavy conservative opposition.

Rubio said the legislation was never going to pass without popular support, and the United States needed to begin enforcing immigration laws and improve border security before the public would have the confidence to back it.

“The question is did he fight for his legislation. It’s abundantly clear that he didn’t,” Christie said.

BUSH TUSSLES WITH TRUMP

Bush attacked Trump for using eminent domain, which allows governments and other public entities to seize private lands for projects for the public good, to help him build casino complexes in Atlantic City.

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

Trump said eminent domain was “a good thing” and was necessary to building roads, bridges, schools and hospitals. “Certainly, it’s a necessity for our country,” he said.

“He wants to be a tough guy, and it doesn’t work very well,” Trump said of Bush, telling the former Florida governor to be quiet. When the crowd booed, he said, “that’s all his donors and special interests out there.”

Trump, known for his tough stances with calls to ban Muslims from visiting the United States and deport immigrants without the proper documents, also called for a more compassionate approach to the Republican call to repeal Obamacare insurance coverage for Americans.

"There will be a certain number of people who will be on the street dying, and as a Republican I don’t want that to happen,” he said. “We are going to take care of those people and I think everybody on this stage has to agree we’re not going to let people die sitting on the street in any city in this country.

Cruz bypassed an early chance to tussle with Trump, refusing to repeat his criticism from earlier this week that he did not have the temperament for the White House.

Trump noted that Cruz did not want to take him on.

"He didn't answer your question, and that's what's going to happen with our enemies and the people we compete against," Trump said. "We're going to win with Trump and people back down with Trump, and that's what I like."

Trump and Rubio have become the favored targets of the other Republican candidates this week as the candidates launched an all-out offensive across New Hampshire.

A Suffolk University/Boston Globe poll on Friday found Trump leading with 29 percent, followed by Rubio and Ohio Governor John Kasich.

Not on stage was businesswoman Carly Fiorina, who failed to meet host ABC's qualification debate requirements. Fiorina released an open letter excoriating the debate process as "broken."