I read both sides of the Natural Born Citizen arguement. The Supreme Court is going to have to decide this sooner or later. But, if Rubio is chosen for the VP slot, and his NBC status is challenged, that would force a call from the media for Obama to prove that he is a NBC.
Personally, I think the Tea Party should be working hard to see that each state has a constitutional eligibility requirement on the books. Keeping Obama off the ballot would be one way to further our cause. Then maybe a third party would have a chance.