There was another President of Unistat who resigned, actually, but he "only" (as they say) existed in a novel. This was a science-fiction thriller set in a parallel universe and was called Wigner's Friend. It was about the worst possible President the author, a Harvard professor named Leary, could imagine.

The President in Leary's book, called Noxin, was a monster. He got the country into totally unnecessary wars without the consent, and sometimes even without the knowledge, of Congress. He lied all the time, compulsively, even when it wasn't necessary. He put wiretaps on everybody -- even on himself. (Leary, a psychologist, claimed this bizarre fantasy, which smacked of satire, was possible, for a certain type of paranoid mind.) He used the FBI and the IRS to harass every citizen who resisted this tyranny. He not only took bribes, but even had a team of enforcers who extorted "campaign" money from corporations under the threat of turning the IRS on them. His political enemies all died in a series of strange assasinations that couldn't be explained. When Congress started investigating his crimes, he betrayed his co-conspirators one by one.

Noxin even misappropriated government money to fix up his house, and cheated on his income tax.

The book was a runaway best-seller, because it had a taut, suspenseful plot and because the Unistaters could congratulate themselves on not being dumb enough to ever elect such a President.