If the previous GOP debate led to the undoing of Marco Rubio in New Hampshire, Saturday night's brawl in Greenville, S.C. , by rights should cost Donald Trump his sizable lead in the Palmetto State.

If South Carolina Republicans were really listening with open minds, they heard Trump blame George W. Bush for 9/11, repeat the left-wing belief that Bush "lied" us into the Iraq war (i.e. it was a matter of intent, rather than acting on faulty intelligence), defend Planned Parenthood and Vladimir Putin, and generally speak like someone who would be more at home in the Democratic primary.

All of this came as Trump very obviously was nettled by Jeb Bush, in a way that undermines his claim to be a "winner" who can't be brought down by such a "low energy" opponent. Trump very frequently, in exchanges with Bush and Ted Cruz, resorted to yelling "liar, liar" in the way of one whose appeal is nothing but force of personality rather than substance or specifics.

(Of course, nothing Trump says or does costs him any support, so he'll probably clear 40 percent in the primary six days from now.)

If any candidate was in need of a rebound, it was Rubio. And he delivered. He gave a perfect distillation of what made the late Antonin Scalia a great jurist and a model for future Supreme Court justices: He "understood that the Constitution was not there to be interpreted based on the fads of the moment, but it was there to be interpreted according to its original meaning." He gave a thorough response about why he voted against President Obama's plan for military action in Syria as something that "would not only not help the situation, it would make it actually worse. It would allow Assad to stand up to the United States of America, survive a strike, stay in power and actually strengthen his grip." He gave the right defense of George W. Bush in a tangle with Trump. He defended his tax plan, which would leave the top marginal income-tax rate higher than other candidates' plans would, but would also ease the burden of many families with children:

"Let me tell you, if you're a parent that's struggling, then you know that fifty dollars a month is the difference between a new pair of shoes this month or not getting a new pair of shoes for your kids. I'm going to have a tax plan that is pro-family because the family is the most important institution in society. You cannot have a strong country without strong families."

And he came out with no worse than a draw with Cruz in yet another argument between them about who said what when about immigration reform. All in all, it was an effective night for Rubio, one that ought to put to rest the notion that he's a shallow, pre-programmed, "pretty face" of a candidate.

Cruz was up and down. As I mentioned, he did not land much of a blow on Rubio on immigration, in largest part because he does not want to own up to his own words from three years ago. On the other hand, he was the one who drew out Trump on the question of the businessman's, ahem, evolving opinions on the major issues. He said, very believably, that Trump's history suggested he would appoint liberal justices to the Supreme Court. His defense of his own tax plan was less persuasive; most neutral economists, as far as I can tell, agree Cruz's plan for a business flat tax is practically indistinguishable from a European-style VAT, which is the tool that really lets European governments suck money out of the private sector.

Bush was feisty once again, and he took the fight to Trump like no one else. While he sullied Trump in some of those exchanges, I'm not sure he necessarily boosted his own prospects; I'm reminded of Chris Christie's attacks on Rubio in the previous debate, which hurt Rubio but didn't help Christie. Campaigning with his brother next week brings the family tie to the fore. While that may go over well in South Carolina, I'm not sure it's a winning strategy in the long term in a party that is still ambivalent, at best, about Bush 43 and that family dynasty.

John Kasich was once again sort of off to himself. He didn't engage the other candidates except to try to portray himself as above the fray in which they were mired, and other than one brief exchange in which Bush criticized his expansion of Medicaid, Kasich scarcely drew the other candidates' attention. I still think he has to make his play elsewhere to remain viable in the race.

Ben Carson was the same as always. It astounds me that he's still in the race and invited to these debates. He even spiced up his closing remarks with a fake quote from Joseph Stalin . He will not be the nominee.