Republicans have a habit of portraying anything they oppose as the “other,” foreign to good true patriotic (white christians with high school educations) Americans. They often do it by pointing out someones educational background (they went to Harvard, you didn’t go to Harvard, so they’re not like you, and they don’t understand you). In this case it’s obvious that the most defining difference between Obama and the Republican base is his race, so they have to use that to prove that he doesn’t understand “real” America. Only catch is they can’t come right out and say his race makes him unqualified, so they have to pretend like he’s simply foreign, since we all know foreigners have a fundamentally different and twisted view of the world.