I would love to be corrected on this by someone who understands the US constitution better than I do, but as I read the 25th amendment, it has – with small differences – the same problem as impeachment. There aren’t the votes to make it stick.

Quick summary for those who are less on Bluesky than I am.
The US Constitution allows a President (or any office holder) to be impeached for high crimes and misdemeanours. The House prepares articles of impeachment – the charge sheet, if you like – and the Senate has to vote by a two thirds majority to remove the person from office.
The key point there is the two-thirds majority – sixty-six Senators, in other words, when the current split in the Senate is 53 Republicans, 47 Democrats, and 2 others – both of whom vote with the Democrats most of the time.
Because this bar is high – more than 20% of the elected Republicans would need to switch sides – it is unlikely to succeed, at least until the election in November chooses another House and 33 new Senators to take office in January.
Because of this high bar, a lot of people, not just online politics-heads, have been calling for the 25th amendment to be used. This was brought in for periods of temporary disability (for instance, if the President has had an accident, or is under anaesthetic for an operation).
Section 4 of this amendment allows the President to be temporarily stripped of his powers (while remaining President). However, it’s not as simple as people think, there are two big stumbling blocks.
The first is in the first line of the section:
Whenever the Vice President and a majority of either the principal officers of the executive departments or of such other body as Congress may by law provide, transmit to the President pro tempore of the Senate and the Speaker of the House of Representatives their written declaration that the President is unable to discharge the powers and duties of his office, the Vice President shall immediately assume the powers and duties of the office as Acting President.
It is the Vice President AND, not the Vice President OR – so JD Vance has a veto. Without his consent you can’t use Article 25.
Maybe that’s not too bad – I mean, he’d get to exercise the powers of the President, maybe being dragged for disloyalty on Trump’s Truth Social account would be worth it.
However, the real problem is the second section. If the Vice President has done the dirty (with half the Cabinet) and sent the declaration to the Senate, the President is temporarily powerless. However, in this situation we have to assume that Donald Trump is still there, Truthing away and 100% conscious.
Thereafter, when the President transmits to the President pro tempore of the Senate and the Speaker of the House of Representatives his written declaration that no inability exists, he shall resume the powers and duties of his office
So two minutes after the 25th Amendment is in force, Trump sends a competing declaration to the Senate to say he’s fine, and he takes back his old powers (and presumably fires half his Cabinet).
There is a way around that – the Vice President and a majority of the Cabinet can delay things, but only for four days … and then …
Thereupon Congress shall decide the issue, assembling within forty-eight hours for that purpose if not in session. If the Congress determines by two-thirds vote of both Houses that the President is unable to discharge the powers and duties of his office, the Vice President shall continue to discharge the same as Acting President; otherwise, the President shall resume the powers and duties of his office.
There’s that two-thirds majority again – of both Houses. Not only do you need to get twelve or thirteen Senators to switch sides, you also need to get about seventy Representatives to switch as well.
So the 25th might hold Trump back for a few days – but in the end, he’s back in office and angrier than ever unless you have the same majority you need for impeachment. Impeachment removes him from office completely (though you do then get President Vance).
So – and this is where the Constitution has clearly completely failed – if there is no way to impeach, there is no way to enforce the 25th Amendment.