In theory, yesterday’s briefing at the White House could have, and should have, been a straightforward gathering of policymakers. Donald Trump’s new policy in Syria has created crisis conditions in northern Syria, and this was the president’s opportunity to let congressional leaders know more about conditions on the ground, his policy, and its future.

At least, that was the idea. In practice, Trump couldn’t behave like an adult long enough to lead the meeting.

Democratic leaders in Congress on Wednesday angrily walked out of a White House meeting with President Donald Trump after he had a “meltdown,” according to House Speaker Nancy Pelosi. […] The President started the meeting with a lengthy bombastic monologue, according to a senior Democratic aide…. The meeting quickly devolved into a series of contentious exchanges centering on the president’s decision earlier this month to pull troops from Syria, which paved the way for the Turkish invasion.

There is no public transcript or recording of the gathering, but by most accounts, Trump admonished former Defense Secretary James Mattis for not being as “tough” as him, complained that he didn’t want to even have the briefing he was supposed to lead, suggested Democrats are vaguely sympathetic to ISIS because the terrorist network includes “communists,” and insulted Nancy Pelosi to her face, dismissing her as a “third-rate” politician.

Since the discussion obviously wasn’t going to be constructive, Democratic leaders saw no need to stick around.

The House Speaker described Trump’s bizarre behavior as a “very serious meltdown,” adding that Americans should “pray for his health.” Because the president routinely finds it necessary to respond to every slight in a I’m-rubber-you’re-glue sort of way, Trump published a tweet soon after accusing Pelosi of being mentally ill, adding, “Pray for her, she is a very sick person!” Since he heard the Speaker accuse him of a “meltdown,” Trump also accused Pelosi of having had a “meltdown.”

White House Press Secretary Stephanie Grisham insisted that the president was “measured” and “factual” during the meeting, which people who’ve never seen, heard, or read about Donald Trump might actually believe.

It’s the third time this year a White House gathering has been derailed by a presidential breakdown, following a meeting in January during Trump’s lengthy government shutdown and a gathering in May that was supposed to be about infrastructure.

What strikes me as amazing, though, is the larger context of Trump’s latest breakdown.

It’s in the Republican’s interests to behave like a president, at least when around other people. A scandal is poised to lead to his impeachment; his foreign policy is collapsing into catastrophe; and ahead of his re-election campaign, polls show an electorate ready to make a change in American leadership.

What’s more, many in the White House have gone out of their way to be nice to Pelosi in recent months because they want her help in passing NAFTA 2.0 (or USMCA, or whatever it is we’re supposed to call it now). Trump, on the other hand, recently delivered speeches in which he said the House Speaker “hates the United States” and is “not a good person” – all of which led to yesterday, when he started insulting the Democratic leader to her face.

Common sense suggests Trump should want the public to have some confidence in his ability to function as a mature and capable president. But as the walls close in, he just can’t seem to help himself.