Here's why that cannot be allowed. Another FReeper posted it the other day and I saved it; I'd give credit to the poster but I neglected to save the screen name- sorry.
If the election is not held this year then on January 3rd the House of Representatives is empty. The terms of all Congressmen and Congresswomen end as of January 2nd. In the Senate, over one third of the seats are empty because they were up for election this year. Republicans hold 23 of those seats and Democrats hold 12, so on January 3rd there will be 30 Republican senators and 35 Democrat senators, Chuck Schumer becomes Senate majority leader and the Democrats appoint the President pro Temp, who becomes President on January 20th since Trump's term is up and there is no Speaker of the House.
Then who would that be? The oldest of the remaining senators?