I think he wishes he had skipped the whole damn deal.
I don't think he ever really wanted to run - he was talked into it. Maybe it's that reluctance that comes through in debates.
In his press conference the other day Cain stated firmly that he was running for his children and grandchildren: he feels he has a duty to try to avert the coming American train wreck. That faith may see him through the sleazy attacks. Meanwhile, after this, Cain and Gingrich will split what little support Perry has left.