This question has been covered. There is no shortcut.
Having legislatures refuse to appoint Electors will LOSE THE PRESIDENCY. This does not work. The reason is the Constitution says the vote among state delegations in the House takes place “immediately” but that word is not defined. Pelosi can simply no schedule the vote. Pres and VP term expires Jan 20 and she becomes president.
That vote can be held up forever by Dems in the House, immediately or not, and the USSC will never interfere with the process of Congress.
So forget that. The only winning maneuver is Legislatures — and then are Republican — have to conclude there is so much uncertainty and Trump/Biden only differs by a small number of votes in their state .. . they will use their own best judgement in appointing Electors, and that will be for Trump.
The Electors vote in their state (the “College” is the collection of all of them in their own state, there is no trip to Washington for themm) and an official document from the Legislature is sent to the President of the Senate (Pence). During a joint session he reads the votes and a sum is computed.
Votes can be objected to by any member of Congress as long as their is a second (this happened in 2000). Debate takes place and the presiding officer rules on the objection.
Done.
Now, if some of those legislatures appointed electors to vote for third-party candidates instead, thereby denying any Presidential or Vice-Presidential candidate a majority, the result would still not be President Pelosi. If Pelosi fails to schedule the vote, the Senate can still meet and vote for Vice President. Regardless of the outcome of the GA special election and when its winners take office, Senate will still have a Republican majority on January 6 with Pence's vote, so a result would presumably be (acting) President Pence, not Pelosi. I say "(acting)," because he would cease acting as President once a President is elected.
“Pelosi can simply no schedule the vote. Pres and VP term expires Jan 20 and she becomes president.
That vote can be held up forever by Dems in the House,”
Well, Pelosi’s Democrats will deny a quorum IMO.
Interestingly though, the Senate will have meanwhile determined a new VP, who would assume the Presidential office.
I doubt that the Sargeant at Arms of the Senate will allow Members to avoid a quorum- as would happen in the House.