As Ronny Jackson, MD (Texas R-Congressman, and former WH Physician) has been saying for months— for the good our Natonal Security. The chain of command in very specific circumstances depends on a 1.)sane and 2.)competent even if poor decision making skills.
But, just to be sure, during the Cold War, the Congress passed 2 Acts still in force on the provision of Devolution of Executive Power (intended for any loss of Executive/Pres Succession leadership) by devovling to the US Military senior Chiefs. Seriously. This was in re: nuclear defense.
Honestly, I hope if they can get him to step down, he isn’t declared incompetent, because at that point, at least 4 states will prevent the left from having any chance at all.