The Democrats recently started an official impeachment inquiry over the allegation that Mr Trump pressured a foreign leader, Ukrainian President Volodymyr Zelensky, to launch an investigation into his most likely opponent in next year's election, Joe Biden.
That happened during a private phone call between the pair. We know this, because it's in the White House transcript of the conversation.
Nevertheless, Mr Trump offered a few stubborn denials after the story broke. He accused the media of publishing fake news. He impugned the credibility of the whistleblower who complained about the call.
Those arguments were essentially thrown in the bin on Thursday. They're no longer relevant.
"They should investigate the Bidens," Mr Trump said of Ukraine, with the cameras rolling.
"Likewise, China should start an investigation into the Bidens, because what happened in China is just about as bad as what happened with Ukraine.
"So I would say that President Zelensky, if it were me, I would recommend that they start an investigation into the Bidens."
Yes, I did it. I'd do it again. Heck, I'm going to do it again now, right in front of you. I'm going to do it twice in 10 seconds. I'll even drag in another foreign country for good measure. So what?
That is Mr Trump's new, and it must be said, incredibly bold position.
Imagine Bill Clinton calling a press conference at the height of the Lewinsky scandal in 1998, admitting he had lied under oath and unrepentantly saying he'd do it again.
That is the level of brazenness we are talking about here.
Some people might think it daft for Mr Trump to re-enact an allegedly impeachable offence with the entire world watching.
Fox News anchor Shepard Smith, for example, reacted to the President's remarks with a sort of detached bemusement.
"Today the President did exactly what he's accused of doing, this time on live television. And this time, he asked the totalitarian government of China to investigate his rival ahead, of trade talks scheduled for next week," he said.
"If it is determined that the President made that request to help his campaign for re-election, President Trump may have violated federal law. It is illegal to ask a foreign national or foreign country for any political assistance."
We'll get to the legal argument in a moment.
But impeachment is a political process, not a legal one. And part of me wonders whether, politically, Mr Trump's move was actually a stroke of genius.
We have all been conditioned to expect scandalous acts - even the smallest ones - to be hidden from public view, because they usually are.
Few people cheat on their partner with that partner in the room.
Most drug deals don't happen with a police officer present.
When I wanted to get away with a bad report card, did I leave it on the kitchen counter for my parents to find? No! I hid it in the bushes, like a normal person.
By that logic, if Donald Trump asked a foreign country to interfere in American politics, but he did it brazenly, openly and on camera, how bad can it be?
That is the reaction he's hoping for.
He is relying on the natural assumption, shared by pretty much everyone, that a person who does something wrong should feel ashamed and want to hide it.
Of course, the actual answer to the question "how bad can it be" is that something done in plain sight can still be immoral, perhaps impeachable, and possibly even illegal. If it's the latter, the President just broke the law on live television.
Under US electoral law, it is illegal to "solicit, accept or receive a contribution or donation of money or other thing of value" from a foreign national.
The key question here is the definition of a "thing of value".
If Mr Trump were asking Ukraine and China to donate a million bucks each to his re-election campaign, or even to just buy a few boxes of "Make America Great Again" caps, it would be a slam dunk case.
But would a politically damaging investigation of Mr Trump's opponent be considered a "thing of value" under the law?
I have no idea. The legal scholars are already arguing about it.
"In the President's view, asking a foreign government to investigate a domestic political opponent is not troublesome or problematic," Fox News legal analyst and former judge Andrew Napolitano said this week.
"The problem with that is the statute, which says soliciting - asking - for aid in a domestic political campaign, whether the aid is delivered or not, is a criminal event. That's clear in the statute. Whether the aid is delivered or not, asking for it is impermissible."
It is possible, then, that Mr Trump's comments will help him politically in the short term, but backfire legally once he leaves office.
His defenders still insist he did nothing wrong. They say he pressured Mr Zelensky - and now China, I suppose - out of some heretofore unknown zest for fighting corruption.
It is indeed normal for a US president to push other countries to investigate and crack down on corruption. Of course, that point would feel more plausible if Mr Trump had ever pressed for an anti-corruption investigation into anyone other than his direct political opponent.
In any case, there is no longer any real mystery surrounding his conduct. The President himself killed that mystery when he repeated the conduct in question on camera.
It is always hard to discern the driving force behind his decisions. Strategy or impulse? His brain or his gut?
In this case, it doesn't really matter. Whatever the answer, Mr Trump's abrupt change in tactics can't be reversed.
His cards have been turned over. His chips are on the table. He has committed to a massive gamble, and his survival as President hinges on the result.
