MANCHESTER, N.H. -- The target on Sen. Marco Rubio's back grew larger Saturday, as rival candidates, starting with New Jersey Gov. Chris Christie, sought to turn the Florida senator's polish into a liability in a critical debate on the eve of New Hampshire's leadoff presidential primary.
Meanwhile, Jeb Bush sought anew to take on Donald Trump with a rebuke of his conservative credentials, questioning his enthusiastic support for eminent domain.
The two main clashes in the debate revealed divergent strategies followed by trailing candidates in need of a breakout moment in the crowded field: attack the front runner or try to blunt the momentum of a fast-rising rival.
Saturday's nationally-televised, primetime debate in Manchester offered what was probably the last, best chance for candidates to shake up the field before voters here go to the polls Tuesday.
Trump is trying to sustain his celebrity-driven candidacy after finishing second in the Iowa caucuses, a blow to the New York businessman who has consistently touted his first-place ranking in polls.
But all week it has been Rubio drawing fire from his rivals, a trend that continued in the debate's earliest moments. Christie mocked Rubio after he defended his record of accomplishment in the Senate, charging that he had never been involved in a "consequential decision where you had to be held accountable."
"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," the New Jersey governor said, arguing Republicans shouldn't make the same mistake the nation did eight years ago when it elected Barack Obama, another young senator.
Rubio countered by noting New Jersey faced nine credit downgrades on Christie's watch before returning to his own practiced criticism of Obama. Christie pounced.
"That's what Washington, D.C., does," Christie said. "The drive-by shot at the beginning, with incorrect and incomplete information, and then the memorized 25-second speech that is exactly what his advisers gave him."
As the exchange continued and the two rivals spoke over one another, Rubio cranked up the volume, sweat beginning to glisten on his face. He accused Christie of not wanting to leave the campaign trail to return to his state after a huge snowstorm hit last month.
"You know what the shame is, Marco?" Christie replied. "The shame is that you would actually criticize somebody for showing up to work, plowing the street, getting the trains to run back on time, when you've never been responsible for that your entire life."
The winner of the Iowa caucuses, Sen. Ted Cruz of Texas, sidestepped an early opportunity to directly challenge Trump. Asked whether Trump had the temperament to be commander in chief, Cruz said that was "an assessment that the voters are going to make."
Bush, though, seized an opportunity to question Trump's support for the seizure of private property using the government's power of eminent domain, a controversial practice among many conservatives.
The former Florida governor accused the New York developer of getting state officials to condemn an elderly woman's home in Atlantic City so he could build a parking lot for limousines near his casinos.
"That is downright wrong," Bush said, arguing that eminent domain only should be used for public purposes, such as building schools, hospitals and roads.
Trump defended eminent domain, calling it essential for a modern economy, and mocked Bush for trying to be "a tough guy."
"I didn't take the property," he said.
"You tried," Bush retorted.
The audience booed Trump -- also attracting his ire. Although organizers said the audience included a thousand New Hampshire voters, Trump alleged they were donors and "special interests."
Even though he finished third in Iowa, Rubio has benefited by it, and his campaign has picked up momentum. Averages of New Hampshire polls show Rubio in second place, narrowing the gap with Trump while putting distance between himself and the rest of the field.
Cruz and Gov. John Kasich of Ohio currently are tied for third place, the polling averages suggest.
Bush, Christie and Kasich are especially counting on strong performances that they hope will breathe life into their lagging campaigns. For them, the debate is an opportunity to explain why their experience should matter in an election year when voters seem resolutely uninterested in politician's resumes.
Kasich touted his heavy courtship of New Hampshire voters, including more than 100 town hall meetings. "We have to have practical solutions," he said in response to a question about immigration in which he rejected the idea of large-scale deportations and embraced the idea of a path to legalization – although not citizenship – for people currently in the country illegally.
His statement was emblematic of his pitch as a pragmatic conservative, an appeal tailored to the state's sizable block of independent voters.
Cruz was asked how he would deport people from the country. He laid out a detailed plan, including a border wall and more patrol agents. Pressed again on deportations, Cruz said, "What you do is you enforce the law."
Rubio again sought to explain why he had backed away from an immigration bill he co-sponsored in 2013. He said there wasn't enough backing for the bill and border security must come first.
"The American people have zero trust that the federal government will enforce our laws," Rubio said.
Christie again took on his rival, accusing him of turning tail in the immigration debate without showing leadership.
"It is not leadership to continue to try something that has no chance of happening," Rubio said.
The seventh and final candidate on stage is Ben Carson, the retired neurosurgeon whose campaign has sagged in recent weeks and shows no signs of regaining strength. And he almost seemed reluctant to even join the stage, standing awkwardly in view of cameras after apparently not hearing his name introduced to the audience.
Each of the seven, with the possible exception of Carson, has the potential to turn the campaign in his favor.
"This race is up for grabs, and can go any which way," said Andrew Smith, director of the University of New Hampshire Survey Center. The debate could play a particularly important role because many of the state's voters make up their minds late, Smith said.
Saturday night represents "the last opportunity for some of these candidates to break out," Smith said.
Saturday's debate was a smaller affair than previous overstuffed debates, representing a slimmed-down Republican field. Sen. Rand Paul of Kentucky, former Arkansas Gov. Mike Huckabee and former Sen. Rick Santorum of Pennsylvania all dropped out this week.
In addition, there was no undercard debate for candidates who have trailed too far behind in the polls to make the cut. That means Carly Fiorina, the former Hewlett-Packard executive, and Jim Gilmore, the former Virginia governor, didn't get a shot at speaking in front of a national television audience Saturday night.
Fiorina, who received less than 2 percent of the vote in the Iowa caucuses on Monday, has complained bitterly about ABC's decision to stick with its announced criteria for who would participate in the debate. She told MSNBC on Friday that her exclusion was proof the game was "rigged."