Forget the mistress for a moment. Let’s say what Sanford spent the money on is unimportant. He stole public funds for private use. Let that one sink in there. He stole the money he used for his trip.
Forget the mistress for a moment. Let’s say where Sanford went is unimportant. He left without letting anyone - his office, the people assigned to protect him, his own family - know where he was going. Let that one sink in there. He skipped out on doing his job without anyone having a clue where he went.
So for your analogy to work Obama would have to raid the treasury and then jet off to another country without even the secret service knowing what was going on. If that happened, yes, I wouldn’t vote for him. I consider theft and abandoning your post a rather large breach of the public trust. Clearly the people of his district feel otherwise.
As the money was stolen the answer is whatever you think you can get away with. Clearly it’s going to be less than Sanford had to play with as he got caught.