[The Pack Knight]

There was a fairly recent Texas Supreme Court case, Pressley v. Casar, involving a challenge to an Austin city council election. The challenger lost in the trial court and the court of appeals, and appealed to the Texas Supreme Court. But while the case was pending in the Texas Supreme Court, the winner was re-elected and his new term had already begun. The Texas Supreme Court dismissed the case as moot, because a challenge to an official’s election becomes moot when the official’s term expires.

It is hard to see how the exact same principle would not apply to a challenge of the appointment of a presidential elector after he has voted. The only way around it is to ignore, as many do, the distinction between a state’s appointment of electors and the actual presidential election. It is clear that Trump’s own lawyers understood, though, that their challenges would become moot some time between the “safe harbor” date and January 6.

[Bruce Campbells Chin]

At the barest minimum, you'd need the Supreme Court to endorse such a move, and that's just not going to happen. A state reversing/decertifying electors in between the time they are certified and the Electoral College vote would be a different question. But once the EC is voted, it seems no different than would a member of Congress deciding a month after a bill passed that he should have voted differently, and expecting that to repeal the law after it was already signed.

The Electors have voted, and one state deciding after the fact that it changed it's mind isn't going to change that.