Truly hope none of this comes to pass, but here's the legal and Constitutional machinery that could activate if necessary.

Thread:

1) Under the 25th Amendment, the President can voluntary and temporarily transfer power to the VP if the president is or will be "unable to discharge the powers and duties of his office." This has happened several times, recently when GW Bush underwent routine medical procedures.

2) The 25th Amendment also enables the VP, joined by a majority of Cabinet officers (some uncertainty about exactly who qualifies), to certify in writing to Congress that the President is "unable to discharge the powers and duties of his office." If so, VP takes over, but:

3) The President, once recovered, can certify to Congress that he is no longer incapacitated. He then re-takes power. (VP and Cabinet can challenge this, and Congress can decide, but that shouldn't be applicable here).

4) The election date is set by federal law for the Tuesday after first Monday in November (Nov. 3, this year). That date can be moved by federal statute -- meaning you'd need House majority, Senate majority, and Presidential signature.

5) Federal law also sets important Electoral College dates -- this year, Dec. 14 for votes to be cast in states, and Jan. 6 for Congress to formally take those votes. Those dates also can be moved by statute.

6) BUT: the Presidential term ends at noon on January 20, under the Constitution (20th Amendment). That can *not* be changed by statute; a change would require a Constitutional amendment, which is almost impossible in time (need 2/3 of House, 2/3 of Senate and 3/4 of states).

7) If there's no Constitutional amendment and January 20 arrives with no newly-elected President and VP, then succession kicks in and the new Speaker of the House takes over temporarily.

Again: let's all hope none of this becomes necessary. But there are rules if it does.