imgflip.com/i/8xsfcq
I think he was threatened with something other than the 25th. That process takes too long. First, the cabinet has get together and take a vote. Written demand has to be delivered to the president. There is a 30 day rebuttal period for the president. If the President does not accept the demand to resign the office, then the House of Representatives is required to hold hearings before taking a vote to remove the president.
That can’t be done in time to get a name on the ballot in many states.