What did Donald Trump do today?

He planned and successfully executed a tantrum.

Trump was scheduled to meet with Democratic leaders Nancy Pelosi and Chuck Schumer today to talk about infrastructure plans. That is not what happened. Instead, reporters were summoned to the Rose Garden, where Trump vented his anger that Pelosi had said that he was engaged in a cover-up. 

The "impromptu" Rose Garden press availability, which happened as Pelosi and Schumer departed the White House after what turned out to be a three-minute meeting, was clearly planned in advance. Trump read from extensive notes he had written in his trademark marker pen, and spoke from a podium with a printed placard bearing factoids about the Mueller investigation.

(The pre-arranged snit did have the effect of getting Trump out of an awkward meeting, though: Trump's own infrastructure plan was already dead on arrival, thanks to criticism from Republicans: even his own chief of staff wouldn't publicly support it.)

But setting theatrics of the walkout aside, there was a very serious threat in Trump's outburst. He explicitly said that all normal legislative work between the White House and Congress would stop as long as Congress was investigating him. 

So I’ve said from the beginning, right from the beginning, that you probably can’t go down two tracks. You can go down the investigation track, and you can go down the investment track or the track of “Let’s get things done for the American people.”

...So I just wanted to let you know that I walked into the room and I told Senator Schumer and Speaker Pelosi, “I want to do infrastructure. I want to do it more than you want to do it. I’d be really good at that. That’s what I do. But you know what? You can’t do it under these circumstances. So get these phony investigations over with.”

Later, he tweeted, "You can’t investigate and legislate simultaneously - it just doesn’t work that way. You can’t go down two tracks at the same time." Democratic aides confirmed that Trump said as much to Pelosi and Schumer, too.

As many news outlets immediately pointed out, presidents can do both things at the same time, if they want to. Neither President Nixon nor President Clinton refused to cooperate with Congress while their impeachments were under consideration. In fact, some of Nixon's signature legislative accomplishments happened under the specter of impeachment by a Democratic-controlled Congress.

So what?

• Presidents don't get to pick and choose which of parts of their jobs they feel like doing.

• Under the circumstances, a fake and prearranged presidential temper tantrum is not really any better than a genuine and spontaneous presidential temper tantrum.

• The president is not above the law.