I like Cain. But someone on here made a comment that had a lot of merit. The VP is always someone with experience in Washington politics, at the federal level. He listed compelling evidence to back up this history. Biden for Obama. Cheney for Bush. Quayle for Bush Sr. Gore for Clinton. Ford for Nixon....etc. All of them held office in congress or at the cabinet level, etc.
I'm sure this rule will be broken eventually. Maybe in 2012?