George H.W. Bush was done in by the "indictment" of Casper Weinberger just prior to the election by the special prosecutor. There was no prosecution and the charges were dropped after the election, but it had the desired effect.
Along that line, I have worried about Bush leaving Clinton U.S. Attorneys in place. I wonder if one of the Clinton hang-overs could be preparing an indictment of some high Bush official over the prosecution of the war. If it were late enough in the cycle it could generate a LOT of negative vibrations which could stir the pot. Even totally baseless charges would provide just the fodder the MSM could run with for a few weeks just prior to the election.
Of course, that begs the question of why Bush elected to leave so many of the Clinton un-dead in place to begin with. Top it off with Hillary's surprisingly emphatic remark about the election's outcome being determined by an outside event.