Something I mentioned the other day, EV, is that the birther nonsense is a nightmare for the GOP. The reason Obama doesn't prove it is because by holding his ground and not playing their game, which won't matter to them anyway, he's letting them continue to throw up a smokescreen that detracts from their perceived strengths. USA today isn't talking about he differences in how they'd handle the economy. They're talking about an issue that's been proven false, yet continues to simmer.
Obama and his advisors should be doing everything they can to help the birthers perpetuate their bullshit.