Inbetween a number of nasty (and at this point tiresome) exchanges between Cruz and Rubio, one guy on the stage stood calm and collected in the face of constant attacks and immature interruptions from Donald Trump. Apart from one criticism of Kasich on Medicaid expansion, Bush stayed focused on the prize, and came out the clear winner.

Unlike the other debates, where Bush always looked like he was standing there waiting for Trump to take his lunch money, tonight he was confident, in command of the facts, and relentless on the attack. He stayed on message. He wasn't flustered by the same kind of behavior that Christie used on Rubio last week. When Trump continually interrupted him, he calmly talked over him, and repeated points that he thought the audience might not have heard.

By the end of the night, Trump looked like he was on the verge of having a stroke. Even when he was under fire from the other candidates, he repeatedly turned on Bush and tried to talk over literally everything he said. I really think Bush exposed Trump's supposed invulnerability to direct attack was mostly a paper tiger. He can be attacked, with substance, and he can be flustered and knocked off his game. Quite easily, in fact.

I'm sick to death of the back and forth between Cruz and Rubio. For the ninth debate in a row we heard the same dumb argument, only louder. All of America is sick of it by this point. Get over it. I thought both candidates had decent moments in the debate and Rubio probably quelled any lingering fears about his ability as a debater, but I was just so tired of the argument I knew was coming that I was extremely put off by both candidates.

The problem right now is neither Cruz, nor Rubio, and I'm sick of the two of them pretending like it is (and riling up their supporters to believe that in the process). The problem is Trump. The idea that he cannot be diminished and that no portion of his support is vulnerable is absolute rubbish and I'm tired of the posturing to the contrary.

They say Donald Trump has succeeded because he tapped into frustration with "the establishment" that no one was speaking to. Well, there's a frustration with Trump and the increasingly moronic and outrageous things he says and right now only one person is speaking to it competently, and that's Jeb Bush.

And Cruz and Rubio ignore that dynamic in favor of sniping at each other at their own peril.