Donald Trump Jr. just blew apart his father’s “no collusion” case.

The most striking thing about the story that has dominated the news for the last three days—that Trump Jr. met with a Kremlin-connected attorney after being promised damaging information about Hillary Clinton in an email—is just how dumb it is. Young Donald’s story changed drastically with every new revelation, as if he had forgotten that there was an email in his inbox backing the whole story up. The fact that Trump Jr. would leave an electronic paper trail for an at least mildly treasonous meeting suggests a level of naivety and/or privilege unmatched in recent American political history. More importantly, even if nothing came of this meeting, Trump Jr. has destroyed his father’s repeated insistence that there was no collusion between the campaign and the Russian government during the election.

To a large extent, this has always been an absurd argument, given how much Trump and his campaign did to amplify material released by the Russian hacks. (You will recall that Trump even publicly called for more hacks.) But Trump’s own son, who played an outsized role in his campaign, has now been shown to have set up a meeting about information he thought had been acquired by the Russian government for the expressed purpose of aiding his father’s campaign. The Trump campaign’s plausible deniability was never all that plausible to begin with, but these revelations have smashed it to dust.

This is a big problem, and Trump and his allies don’t yet know quite what to do about it. After vociferously defending his daughter Ivanka’s right to sit in his chair during a conference of the G-20, Trump has been notably silent about his son’s actions. That may reflect the very obvious favoritism that defines the Trump family’s relationships, but it also suggests that Trump doesn’t know what to say about the story that has defined and profoundly damaged his presidency. Over the last few days, Trump Jr. and some of the administration’s flacks have tried on a new narrative: 

In other words, who wouldn’t meet with a foreign power promising damaging information on an opponent? That’s a terrible argument for obvious reasons, but it might be the only one they have left.