Don't interpret polls that measure opinion on the real issues that threaten the prosperity and safety of that 53% to be some sort of plebiscite on tortured and obscure eligibility issues.
You'll find that most people who oppose Obama might agree if asked if he show his BC, simply because they have good reason not to trust him, but they don't give it much thought otherwise.
Birthers think Obama is “coming for them?” They don’t get it, apparently. Obama is gunning for the conservative Tea Party movement itself with this little stunt. The left (and Lady Liability) have successfully destroyed the credibility of the eligibility movement. The MSM and DNC tried to destroy the Tea Party by labeling them as racists. That isn’t working out quite so well. So Obama pulls out his Ace. “The Tea Partiers are BIRTHERS!”
The MSM will run with it.