The tipping point came just before 6pm on Tuesday night. Almost simultaneously, Mitch McConnell, the Republican leader in the Senate, and congresswoman Liz Cheney, the third ranking Republican in the House of Representatives, made clear they have abandoned Donald Trump.
It was the moment the political sands shifted under the president's feet. Other, previously loyal, Republicans will follow. And the way is now clear, not just for Republicans in the House to join Democrats in impeaching Mr Trump, but potentially for the Senate to convict him.
Mr Trump would be the first US president to meet such an ignominious fate. Hours earlier it had still seemed a very remote possibility.
Mr McConnell is a quietly spoken individual, but when he strikes he is lethal. Nothing he does is without calculation.
On Tuesday, perfectly timed for reporting on the evening TV news, the New York Times carried a bombshell that Mr McConnell had "told associates" his thinking. And it was devastating.
He now "hates" Mr Trump, it was said, and believes the president has committed impeachable offences. He would be "pleased" if Mr Trump was impeached because it would help to "purge" him from the Republican party.
Mr McConnell does not do things by half measures. Tellingly, there was no denial of the report from his office.
Within minutes Ms Cheney was out with a blistering statement saying she would join Democrats in voting to impeach. Dick Cheney's daughter did not hold back either.
The effect was to send a message from the Republican leadership to its 211-strong caucus in the House. The rank-and-file members of Congress are free to vote with the 222 Democrats to impeach. It is a vote of conscience.
White House officials had thought up to 20 Republicans might do so. But it may now be many more.
Perhaps more significantly, Mr McConnell's "associates" also indicated that he personally may vote to convict when Mr Trump is tried in the Senate.
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For Mr Trump that would be earth-shattering. When in doubt Republican senators tend to follow their leader. And Mr McConnell, not Mr Trump, is their leader.
Only 17 of the 50 Republican senators would need to join Democrats to convict the president. Ultimately, Mr McConnell's move sets up a seismic split in the party.
He has clearly taken the view that the short term pain of exorcising Mr Trump will be worth it in the long run.
Allowing Mr Trump to run again for the Republican nomination in 2024 would create all sorts of chaos.
Mr McConnell, it seems, has calculated that losing some of the president's most loyal following would be less damaging than the exodus of moderates that would occur if he and other leaders stand by Mr Trump.
For Mr McConnell it is all about winning. The bald facts are that in 2016 Republicans controlled the White House, the Senate and the House.
After four years of Mr Trump they have lost all three.
By his calculation, jettisoning Mr Trump cannot actually make things worse.
From Mr Trump's perspective he made a politically fatal error alienating Mr McConnell, who now regards him with cold fury.
The two men have not spoken since Dec 14 after Mr McConnell congratulated Joe Biden on his election win.
Mr Trump did call, but McConnell is said to have refused to speak to the president. By his calculation Mr Trump is a loser, and a bad one at that.
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