What's the mechanism for keeping Trump off 2028 ballots?

The OP still hasn’t been answered. The question is where in the convoluted process of choosing electors, having the electoral college vote, the joint session of congress to count the vote and the inauguration, does the 22nd amendment get invoked and who is responsible for it? SCOTUS seems to feel the states cannot keep him off the ballot and the presidential candidates aren’t really on the ballot. So where in this crazy process does it end? Not clear, not clear at ll.

It is not clear if an elector can vote for somebody who is ineligible. If they can, then the objection could come at any time between when the ineligible person is declared election and when their term would begin. This would open up a whole new can of worms - who would be President? Possible answers include:
(a) The person was elected President, but does not qualify, so the elected Vice-President becomes President
(b) The votes for the ineligible President are considered not to have been cast, so whoever received a majority of the valid votes is President;
(c) The votes for the ineligible President are considered to have been cast, but cannot be counted for this person, so, no person having received a majority of the votes cast, it goes to the House of Representatives…which brings up two more questions: can the House vote for this person, and if it does, who becomes President? (My guess: (1) yes, since the Constitution does not prohibit it; (2) the elected Vice-President.)

However, the answer to all of the questions is, almost certainly, whatever the Supreme Court says they are.

If you’re referring to Trump vs. Anderson, I don’t see that as a covering all-scenarios decision. Rather, there was a narrow, specific point of law that needed to be addressed:

The U.S. Supreme Court restored Republican presidential front-runner Donald Trump to the Colorado primary ballot, ruling that the state lacked authority to disqualify him after his actions three years ago during the siege on the U.S. Capitol.

Six Colorado voters argued that Trump had run afoul of a post-Civil War law that bars people who took an oath to support the Constitution from engaging in an insurrection or rebellion. Section 3 of the 14th Amendment has never been used against a presidential candidate, and it’s only been deployed eight times since the 1860s.

That sparse record contributed to the high court’s decision Monday.

“Because the Constitution makes Congress, rather than the States, responsible for enforcing Section 3 against federal officeholders and candidates, we reverse,” the court decision concluded.

Which amounts to …

Only Congress can keep trump off the 2028 ballot. If there is one. The first hours of the trump regime suggests that’s not real likely.

I for one refuse to dignify the next 4 years with the term “administration”; it’s a “regime” right out of the starting gate.

And will need a regime change to end. With all the disruption, angst, and possibly bloodshed that term implies.

If you actually examine the BALLOTS, it says the Presidential candidate’s name. Not that of the electors.

Yes, their names are on the ballot, but you actually vote for the electors. Even if a state keeps the name off the actual ballot, you will still be able to vote for the electors who promise to vote for him.

I should have said that they needn’t be on the actual ballot paper.