Doesn't the Speaker's or the President Pro Tempore's ascension to Acting President depend on their resignation? They could simply decline it, right?
And if they did ascend, if they nominated and confirmed a Vice President, would that Vice President immediately become President?
This was a very real question in 2000. If the FL recount had not been resolved by SCOTUS, there were various legal groups investigating what might happen if FL electoral votes did not arrive for Congress to count them. Speaker Hastert was considering the possibility that he might be called upon to serve as Acting President until the FL situation was resolved. He was considering whether or not to accept if called upon.
nb. I'm going to delete your post in the ancient thread even though the title there might be more appropriate.
One of my professors said that Florida would have remained unallocated and the election would've gone to the House