In Republican Debate, Rivals Jab at Marco Rubio to Try to Slow His Rise

Mr. Rubio, facing the fiercest attacks yet of the Republican race after his strong third-place finish in the Iowa caucuses, looked rattled at times and faltered as he pushed back with scripted lines about President Obama that Mr. Christie mocked mercilessly.

While the Republicans clashed on issues like abortion and torture, the concerted effort to take down Mr. Rubio dominated the debate, The New York Times reported.

Former Gov. Jeb Bush of Florida and Donald J. Trump also pounced on Mr. Rubio, whose rising popularity in New Hampshire poses a grave threat to their candidacies. But it was Mr. Christie who was the most pointed and personal in his derision of Mr. Rubio — a strategy that may not ultimately bring him votes, but could wound Mr. Rubio just as he has been ascending.

“You have not been involved in a consequential decision where you had to be held accountable — you just simply haven’t,” Mr. Christie told Mr. Rubio early in the debate. Charging Mr. Rubio with taking credit for policies but then skipping Senate votes on them, he said, “That’s not leadership. That’s truancy.”

Mr. Rubio seemed most unsettled when, during the early exchange with Mr. Christie, he attempted to pivot to attacking Mr. Obama for “trying to change this country” and leading the nation to “disaster.” Mr. Christie pounced, suggesting that Mr. Rubio was simply reciting rehearsed sound bites.

Taking a lecturing tone with Mr. Rubio, Mr. Christie said, “See Marco — Marco, the thing is this: When you’re president of the United States, when you are a governor of a state, the memorized 30-second speech when you talk about how great America is at the end of it — it doesn’t solve one problem for one person.”

When Mr. Rubio responded with a line he had used earlier, Mr. Christie looked at the camera with seeming exasperation: “There it is. There it is. The memorized 25-second speech. There it is, everybody.”

Mr. Bush appeared almost itchy to pile onto Mr. Rubio, at one point saying to Mr. Christie, “Chris, why don’t you mention my name so I can get into this,” and then mocked Mr. Rubio for inexperience.

Mr. Christie’s blistering attack may have rocked Mr. Rubio, but it is not clear that will also lift Mr. Christie. The New Jersey governor, after rising in New Hampshire polls at the end of last year, has fallen after facing an onslaught from a “super PAC” supporting Mr. Rubio. Often when one candidate attacks another in a crowded field, a third candidate benefits.

Mr. Trump, who skipped the last debate in Iowa and may have paid a price with voters there, struggled to re-establish himself as a force to be reckoned with on Saturday night. After several debates where Mr. Trump and Mr. Cruz were the most aggressive candidates, they appeared to be protecting their political advantages as they look to build on the Iowa caucuses and the New Hampshire primary for a protracted fight for the nomination. At one point, however, during an exchange with Mr. Bush, Mr. Trump took aim at the audience — a risk so soon before the state’s primary.

“He wants to be a tough guy, and it doesn’t work very well,” Mr. Trump said of Mr. Bush. As Mr. Bush sought to interrupt him, Mr. Trump told him dismissively, “Quiet,” setting off booing in the audience. Mr. Trump denounced those booing as “all of his donors and special interests,” drawing more jeers. “The reason they’re not loving me is I don’t want their money,” Mr. Trump said.

Mr. Cruz, who came in first in the Iowa caucuses, was a low-key presence on Saturday as he sought to have a respectable finish in New Hampshire and move on to more fertile ground in South Carolina. Mr. Cruz ducked when asked if he stood by his earlier criticism of Mr. Trump’s temperament and his assertion that Mr. Trump might use nuclear weapons, even against a friendly country like Denmark. Instead Mr. Cruz simply said that voters would assess who was “levelheaded” and had “judgment.”

The scornful tone throughout the debate even crept into the candidate’s closing statements, which are usually optimistic. Mr. Trump, who made the final closing statement, could not resist besmirching Mr. Cruz’s victory.

“That’s because he got Ben Carson’s votes, by the way,” Mr. Trump said, “but we won’t say that.”