In the case of Weiner, I'm totally behind him under the Fidel Formula.
Whatever his record as a congressman, the guy didn't violate any significant tenet of Democratic Party doctrine and he's not morally much worse than anybody else in congress. He sexted a few women at leisure and then lied trying to cover his shit up. He has to atone with his wife and voting constituency. If, through a recall, referendum, new election, whatever, the guy is kicked out of congress by the voters, he should leave gracefully. But he should not yield to the hypocrisy of the culture and political system, let alone to the intentions of his political enemies. At this point, his only redeeming obligation is to fight with everything he has to retain his seat in congress, show what kind of a dogged politician he can be. The Democrats (and here I make no distinction between the machine and the regular people who vote or simply sympathize with the DP every once in a while, because for all practical purposes -- by action or omission -- they are the true substantive content of the DP) should defend the guy and show everybody how they fight for the underdog against a lynch mob.
Obama is calling Weiner to resign. He should flip the finger at Obama -- and say, "Wimp! I may be a 'perv' or whatever Murdoch's press may call me today, but at least I am a political fighter!" And then let the chips fall where they may.