Third Republican Presidential Debate: The 6 Moments That Mattered

— -- At times it seemed the night was defined not by the candidates’ attacks on each other, but on the moderators who lobbed challenging and, at times, contentious questions at them.

Some fought back and some candidates, including Marco Rubio, John Kasich and Chris Christie, came out looking strong. But others, most notably Jeb Bush, needed a breakout moment that never came.

Here’s a look at the six moments that mattered at the third Republican presidential debate:

1. Rubio and Jeb take off the gloves

They were once friends, but no longer.

Marco Rubio, who considered Jeb Bush a mentor, was first asked about Wednesday’s Sun-Sentinel op-ed that called on him to resign.

He called the paper biased, but Bush, a former Florida governor and a constituent, chimed in, which turned quickly into open warfare.

“Can I bring something up here? I'm a constituent of the senator and I helped him and I expected he would do constituent service which means he shows up to work,” Bush said. “When you signed up for this, this is a six-year term. You should be showing up to term.”

Bush added Rubio should “just resign and let somebody else take the job.”

Rubio jabbed back, saying he supported John McCain’s 2008 campaign and he never complained about his voting record.

“The only reason you're doing it now is because we're running for the same position,” Rubio said. “Someone convinced you attacking me is going to help you.”

2. Ted Cruz vs. The Moderators

Texas Sen. Ted Cruz went for the jugular tonight – but his most vicious assault wasn’t on one of his rivals, it was on the CNBC moderators.

“The questions asked in this debate illustrate why the American people don't trust the media,” Cruz said. “This is not a cage match. Donald Trump, are you a comic book villain? Marco Rubio, why don't you resign? Jeb Bush, why have your numbers fallen?” Cruz added, “How about talking about the substantive issues?”

Cruz was evidently unhappy with the tenor of the questions, which started with the moderators asking each candidate their greatest weakness.

“Nobody believes that the moderators have any intention of voting in a Republican primary,” Cruz added. “The questions being asked shouldn't be trying to get people to tear into each other.”

Later in the debate, moderator Carl Quintanilla noted that he probably wouldn’t be going out for a beer with Cruz. (Cruz offered to buy him a tequila).

3. Kasich launches attacks on Trump and Carson

Ohio Gov. John Kasich had no problem going after frontrunner Donald Trump and Ben Carson right off the bat.

“My great concern is that we're on the verge of perhaps picking someone who cannot do this job,” Kasich said, just days after slamming the two frontrunners on the campaign trail.

“Folks, we got to wake up,” Kasich said. “We cannot elect somebody that doesn't know how to do the job.”

Trump was dismissive of Kasich’s criticism. “He was so nice. He was such a nice guy,” he said. “Then his poll numbers tanked. That is why he is on the end [of the stage.] He got nasty. So you know what? You can have him.”

Kasich, who is averaging just 3 percent in the polls according to CNBC’s debate criteria, used to chair the House Budget Committee.

“I'm the only person on this stage that was actually involved in the chief architect of balancing the federal budget,” he said. “You can’t do it with empty promises.”

4. Donald Trump pushed to the sidelines

For a few sections of the third debate, it was easy to forget that Donald Trump was even on the stage.