Donald Trump (CRISTOBAL HERRERA/European Pressphoto Agency)

Thursday's Republican presidential debate was the 12th and may well be the last one of the GOP race.  That is, if Donald Trump has anything to say about it. “I think we’ve had enough debates,” the Republican front-runner said Friday. “I mean, how many times do you have to give the same answer to the same question?”

It's understandable why Trump would want the debates to end. He's not terribly good at them. And/but Trump had his best debate of the campaign Thursday night (it's a low bar), so he'd almost certainly like to end on a high(ish) note.

The reason Trump was moderately effective in the debate was that he was VERY un-Trump. (It's kind of like being very un-Dude.) He had clearly made up his mind that the mud-throwing part of the race (or at least of the debates) was over and that the time to look, well, "presidential" had arrived. Trump's opening and closing statements focused on how amazing the movement he has built is and why it is necessary now for all Republicans to rally behind him and take advantage of the energy and crowds he is creating. Gone were the dismissive putdowns of his rivals -- "Little Marco" and "Lyin' Ted" -- and in their place was a conciliatory spirit. "I can't believe how civil it's been," Trump remarked at one point, making sure that everyone knew that this was a different Donald Trump they were now dealing with.

That's not really what impressed me. After all, I know Trump is a salesman and marketer at heart. And, as the best people in those fields often are, he is a bit of a shape-shifter -- channeling what he believes his audience wants and giving it to them with them none the wiser. We always knew this kindler, gentler Trump was coming at some point.

What really impressed me was Trump's discipline. It's easy to say you are going to act more presidential. It's even easy to start off a two-hour debate with a message of unity. What's much harder is to stick to your be-calm-and-carry-on game plan in the face of attacks -- especially from someone like Ted Cruz, whom Trump disdains.

The degree of difficulty is ramped up even higher when turning the other cheek is so fundamentally at odds with who you are and how you've experienced success, not only in this race but in life. Trump's entire persona is centered on the idea that if you take a swing at him, he will take 100 swings in response. That he won't play by any rules. That he will pick up a brick and hit you in the head with it in the middle of a fight. Because winning is what matters. And, the way Trump has always won is to dominate.

That Trump was able to subjugate all of those natural instincts for the better part of two hours tells me that (a) he has tremendous discipline when he wants to and (b) he understands that you can't simply insult your way to the presidency. If you had told me before last night's debate that Trump could be conciliatory and even, at times, kind, in the face of attacks from his opponents, I would have told you that I didn't believe he was capable of it. And yet, he was.

Now, one debate does not a campaign shift make. And Trump's glaring lack of even the smallest shred of policy knowledge, which was on full display last night, remains very problematic. But if I am one of Trump's remaining GOP rivals -- or even the Democrats awaiting the Republican winner -- Trump's ability to make a game plan and then have the discipline to execute it would scare me. He is someone who may well be capable of much more than he is given credit for.