If things are really bad in October, look for the Obama DOJ and US Treasury (IRS) to decide they need to review Romney's income tax returns for possible tax fraud. The next step will be to leak information that an indictment is imminent. That will all go away after the election if Romney has not stepped down by then. This would be at the hands of the Obama for America campaign based in Chicago. See Jack Ryan.
Otherwise, Obama will decide to attack Iran for the October surprise. He would likely get in less trouble than if he got Holder to do his work. See article on DOJ going after Gallup.