On the off chance he actually is planning to back out, what would happen?
Alexander Keyssar, a historian at Harvard who is working on a book about the Electoral College, said the process of succession would depend on “the precise moment at which he said, ‘Nah, never mind.’ ”
The party representatives who make up the Electoral College would suddenly have real power rather than a rubber stamp. If Mr. Trump bowed out after winning on Nov. 8 but before the electors met in each state to cast their ballots on Dec. 19, then the electors could have the opportunity to vote for another candidate, Professor Keyssar said.
A majority of the 538 electors would be Republicans, but they might not agree on the best alternative candidate. If no one won a majority of the electors, the contest between the top three vote-getters — one of whom would presumably be Mrs. Clinton — would go to the House of Representatives, where each state would be given one vote, while the Senate would select the vice president. House Republicans hold 33 states to the Democrats’ 14, with three evenly split. It is unclear whether the vote would take place before or after newly elected representatives were seated.
It is also unclear what would happen, Professor Keyssar said, if Mr. Trump bid adieu after the electoral votes were cast but before they were officially counted, per the 12th Amendment, by the president of the Senate before a joint session of Congress in January. And if Mr. Trump left after the votes were counted in Congress but before he was sworn in on Jan. 20, Professor Keyssar said the closest guidance would probably come from Section Three of the 20th Amendment: “If, at the time fixed for the beginning of the term of the president, the president-elect shall have died, the vice president-elect shall become president.”
“Nothing like this has ever happened,” Mr. Keyssar said.