5 takeaways from the Republican debate

But whether he was over-rehearsed or under-prepared, Rubio was off-key as he responded to the attacks.

The opponent responsible for most of them: Christie.

From the debate's outset, he pestered Rubio. "You have not been involved in a consequential decision where you had to be held accountable," he said.

But he then opened up a brutal line of attack in suggesting that the Florida senator only knew how to turn a phrase rather than accomplish something.

"Marco, the thing is this," Christie said. "When you're president of the United States, when you're a governor of a state, the memorized 30-second speech where you talk about how great America is at the end of it doesn't solve one problem for one person."

In answering Christie, Rubio consistently turned to the same talking point, casting President Barack Obama as calculating rather than incompetent, and intent on changing America for the worse.

The fourth time he invoked Obama, though, the audience turned on him, booing the answer. And then moderator David Muir drove in the knife, saying: "The governor wasn't talking about the President."

Rubio rebounded a bit near the debate's end, when he hammered Democratic presidential candidate Hillary Clinton for supporting abortion rights -- and won applause from the audience for it.

Of Democrats, Rubio said: "They are the extremists on the issue of abortion, and I can't wait to expose them in a general election."

Christie, Kasich and Bush know that since they're all competing for the same pool of more moderate voters, there probably aren't enough tickets out of New Hampshire's primary for all three.

But the trio were still happy to unite in attacking the senators in the race (and, in Bush's case, Trump).

The only mild governor-on-governor criticism came from Christie, who noted that Kasich had increased the number of Ohio's government employees. But that followed praise of Kasich's job performance, with Christie saying he'd "done a great job in Ohio."

And Bush, in arguing that money and authority should shift from the federal government to the states, said: "I trust Kasich and Christie to build the roads in their states."

All three turned in strong performances Saturday night -- and their timing couldn't have been better, given Rubio's on-stage struggles and New Hampshire's reputation for voters who make their decisions at the last minute.

Kasich played up his time as the House's lead budget-writer during the surpluses of the 1990s and his record in turning a deficit into a surplus in Ohio.

Bush effectively traded blows with Trump, lighting into him on eminent domain with a brutal response to the real estate mogul's accusations that Bush wanted to sound tough: "How tough is it to take property from an elderly woman?"

And Christie, who risked coming across as a bully in order to knock Rubio down early in the debate, was moving when he talked about drug addiction, linking his position on helping addicts to his stance opposing abortion, saying he wants to support kids after they're born as well as before.

"I'm pro-life when they get out, and it's a lot more complicated," he said.

Still, there are two big questions: Is it too little, too late? And on a Saturday night, how many New Hampshire voters were watching?

They've bashed each other on the campaign trail in recent days, but Texas Sen. Ted Cruz and Trump -- the two top-finishing candidates in Iowa's caucuses -- seemed to want nothing to do with each other on the debate stage.

It was one fight that was conspicuously absent Saturday night, and it contributed to Rubio's awful night. The Florida senator might have been hoping that those two would bash each other -- but it didn't happen, and he clearly was Enemy No. 1.

Cruz had a revealing answer when asked who he expects will win the Super Bowl: "With an eye toward February 20, Carolina," he said, alluding to the South Carolina primary.

Why it matters: New Hampshire's more moderate electorate means it's not a state where Cruz is likely to shine. He could, though, win in South Carolina -- and his campaign's strategy largely relies on racking up delegates in Southern states with March primaries.

Trump's answers were revealing in their own way, demonstrating that his support isn't about an ideological opposition to big government as much as a desire for strength and a sense that the government is incompetent.

At one point, he defended eminent domain, a practice he's used as a real estate developer. Later Trump backed the role of government-sponsored health care, saying: "You're not gonna let people die sitting in the middle of the street in any city in this country."

Trump was restrained for most of the night -- with the exception of a bit of audience-taunting when, during an exchange with Bush, he dismissed those booing as his donors, and with a single shot at Cruz during his closing statement (more on that later).

Cruz made false claims about CNN's caucus-night reporting -- and the network immediately called him on it.

As caucus-goers were still voting in Iowa, Cruz's staffers had wrongly cited CNN in playing up the idea that former neurosurgeon Ben Carson was dropping out of the race.

"My political team saw CNN's report breaking news and they forwarded that news to our volunteers. It was being covered on live television," Cruz said Saturday. He said CNN reported that Carson was suspending his campaign "from 6:30 p.m. to 9:15," and "didn't correct that story until 9:15 that night."

That is untrue.

"What Senator Cruz said tonight in the debate is categorically false," CNN responded in a statement put out while the debate was in progress. "CNN never corrected its reporting because CNN never had anything to correct. The Cruz campaign's actions the night of the Iowa caucuses had nothing to do with CNN's reporting. The fact that Senator Cruz continues to knowingly mislead the voters about this is astonishing."

CNN had reported that Carson would continue campaigning after taking a break at home in Florida. His next stop, reporter Chris Moody said, would be Washington, D.C., for the National Prayer Breakfast.

Carson passed on the opening to go after Cruz directly Saturday night: "I'm not going to use this opportunity to savage the reputation of Sen. Cruz."

But he did say he was "very disappointed that members of (Cruz's) team thought so little of me" that they would believe he was dropping out after all the effort his campaign put into the race. He pointed to his dedicated volunteers and noted that "one even died" -- a reference to an auto accident in which one of his supporters was killed.

Trump, who'd avoided Cruz all night, did take one shot at him at the debate's end. After Cruz cited his victory in Iowa during his closing statement, Trump said: "That's because you got Ben Carson's votes, by the way."

Thought the 2016 debate season couldn't get any weirder? Think again.

At the start of ABC's broadcast Saturday night, Carson -- the second man due to appear on stage -- seemed not to hear his name. So he lingered behind the curtain as other candidates, confused, walked past him.

Soon, Trump -- who apparently had the same problem -- joined Carson in waiting.

And Kasich wasn't introduced at all, until the moderators were told they'd missed the Ohio governor.

Moderator Martha Raddatz defused the situation by pointing to a loud and rowdy audience that made it difficult to hear.

But on television, it was baffling: The names of the candidates came through loud and clear.

Carson -- late to the stage -- quickly disappeared on it. And while he got supportive chuckles from the audience for his cracks about not getting enough air time -- "I thought maybe you thought already I had dropped out," he said -- that's not the way to climb above his fourth-place finish in Iowa.