Impeachment or the threat of impeachment as with Richard Nixon, thus forcing a resignation He is ours as de facto POTUS until 2012. Two chances of removal: Slim and none.
SLIM:
Real Slim. The Writs of Quo Warranto being sought in the Federal District Court of Washington, DC. are appealed by the losers in the cases to the SCOTUS who decide that, "Ya know, a guy whose father was a British Subject is not constitutionally eligible to be President, sorry."
Of course, that could take until 2025, or until the Depression is over, or until the President is Mexican-born.
NONE:
Probably the way to bet. A pity the Stupid Party has (a) No Plan (b) No Leader (c)No Frickin'Clue.
How about a state Attorney General investigating him for election fraud and throwing him in jail for forgery, perjury, extortion of the media companies, campaign finance violations, social security fraud, and charity fraud?
Would that do the job?