Can Trump keep a lid on his resentments after admitting he's been wrong?

Here’s the real test of Donald Trump’s new campaign advisers: How will the aftermath of his Thursday Teleprompter speech go? Trump’s pattern in recent months has been to follow every restrained, on-message speech with an eruption of resentment and outrageous statements, as if the effort of staying on message for an hour or so was just too much for him. And Thursday, Trump not only stayed on message, that message was that Donald Trump has screwed up:

“Sometimes in the heat of debate and speaking on a multitude of issues you don’t choose the right words or you say the wrong thing. I have done that,” Trump said to laughter and cheers from his supporters.

“And believe it or not I regret it. And I do regret it, particularly where it may have caused personal pain. Too much is at stake is for us to be consumed by these issues, but one thing I can promise you is this. I will always tell you the truth,” said Trump, who did not specify which words he regrets saying.

What could Trump possibly say that would be a wild enough backlash to that display of discipline? Remember that a pretty standard convention speech had him, a day later, rambling about whether Ted Cruz’s father was linked to John F. Kennedy’s assassination. Admitting to saying the wrong thing and regretting it should drive Trump over the edge just about enough to accuse Hillary Clinton of time traveling to assassinate Abraham Lincoln.

And if he keeps a lid on it, we’ll have reason to suspect that Kellyanne Conway and Steve Bannon may have actual, literal, magical powers.