"A man you can bait with a tweet is not a man we can trust with nuclear weapons," Hillary Clinton warned us in her acceptance speech last week. And while that description of Donald Trump is accurate, I don't think it fully captures the scale and scope of the problem. Yes, Trump is "thin-skinned" and "easily provoked," but putting it that way implies that he is the passive actor in that process. He is very much not.

The truth is that Trump craves conflict like normal people crave food or water. He feeds off it, draws energy from it, and when it's missing from his life, when he needs a jolt, he'll go out of his way to create it, in any form he can find it, against any target that presents itself, including Gold Star families and fellow Republicans crucial to his election hopes. (In recent days he's even tried to pick fights with fire marshals, for goodness sakes.) The fate of his campaign, his party, his reputation and even his country are less important to him than getting that fix.

Conflict gives Trump a reason for getting up in the morning, which also explains his habit of posting something angry and outrageous on Twitter long before 7 a.m., just to get his day started right. It's his large pot of dark, black coffee. It puts that grim smile on his face.

This morning, of course, there is no such Twitter post.  That's because we are once again at the Chastened Donald point in the Trumpian mood swing, the point at which he placates staff and family by telling them that OK, he knows that he has a problem and from now on he's going to be a good boy. But as we know by now, Chastened Donald is a temporary aberration. Like any junkie, pretty soon he starts looking for his next fix, and who knows how he'll acquire it.

Conflict is crucial to him because only through constant conflict can he constantly reinforce his self-image as a winner. And when he picks a fight and loses? Oh boy.

He lost his battle against the Khan family -- he lost it badly -- and you can tell that knowledge just eats at him. He wants so badly to re-engage, to correct the injustice and humiliation visited upon him. He won't give it up; I guarantee he will return to it over and over again, out of the blue, in the weeks and months to come. And unlike other politicians, he can't satisfy his need for conflict by waging battle on the basis of policy because he knows no policy, and more fundamentally because it doesn't give him the shot of adrenaline that he craves. It has to be deeply personal to count.

And if losing to the Khans can drive Trump batty, imagine what losing to Hillary Clinton will do to him in the months between now and November. Earlier this week, he bragged that he was up by eight points in New Hampshire; in reality, the latest post-convention polls show him down by 15, with 63 percent of likely N.H. voters saying that he is unfit to be president.  In Pennsylvania, the latest numbers show him down 11. In Michigan he's now down 9.

Earlier this week, after the latest CNN poll showed him losing by nine points nationally, he dismissed it as CNN's revenge against him for refusing to appear on that network. Instead, he enthused about the wonderful people at Fox News, urging his followers to keep their TVs tuned to "fair and balanced".

Well, in the Fox News poll released yesterday afternoon, he is down by 10 nationally. As he confessed to a crowd in Florida last night, he doesn't understand it, and bad thoughts have begun to enter his head:

“Wouldn't that be embarrassing, to lose to 'Crooked Hillary Clinton?’”

It is inconceivable to me to want to put a child like this in the Oval Office. His reluctant enablers in Washington, the Paul Ryans and Mitch McConnells and Marco Rubios of the world, tell themselves and the voters that once Trump is elected president, they'll be able to manage him, as if that were true and as if we should somehow find that reassuring.

Well, it isn't true and it isn't reassuring. The executive branch was not designed to serve as some grand kindergarten to manage the neuroses of a conflict junkie. When the founders drew up our constitutional system of checks and balances, they did so as a guarantee against accidents. They did not contemplate that we might consciously install a person as president whom we knew beforehand was temperamentally unfit to hold it, a person elected with a mandate to pull the whole system down.

I too used to think that such a thing would be impossible. Then again, I also used to admire John McCain, even though we disagreed politically. That changed after his selection of Sarah Palin to be his running mate, to be the proverbial one heartbeat away. In my naivete, I thought Palin's nomination would stand forever as the ultimate act of cynicism and political irresponsibility, of risking deep harm to the nation in order to pursue personal ambition for power.

I look at those in Republican leadership today -- those who know better, who see the danger and yet stay silent -- and I understand that putting Palin one heartbeat from the presidency was nothing in comparison.