There are any number of candidates, but I'm not sure anyone else is equal to the task.
Actually, there’s a tie...Carter and Clinton
In those days, JFnK was undermining US foreign policy while meeting with the Communist North Vietnamese in France, while the US was in a shooting war with them in SE Asia.
Bad as Carter is, I think JFnK set the bar pretty darn low over thirty years ago. IMHO, he cost the US much blood, treasure, legacy, prestige, etc. in at least the same league as the killer-rabbit's opponent.
HF