McSweeneys found him:
ZOMBIE RONALD REAGAN
Pro: Probably the most Reaganesque candidate available; if stoked with the brains of the living, should operate in an acceptable fashion.
Con: Long-dead eyes lack that magic twinkle; inhuman groans negatively impact "Great Communicator" status.
More pithy candidate assessments here. My favorite:
NEWT GINGRICH
Pro: Well known.
Con: See above.