Who are the liberal birthers?

41 percent of Republicans say Obama was definitely or probably born in another country.

Why do so many Americans believe such a silly thing? And why are Republicans so much more likely to believe it?

From Poll: 41 percent of Republicans think Obama wasn’t born in America – Birthers – Salon.com

If the media does in fact have a liberal bias, there should be some liberal media equivalent to the birther. What liberal falsehood does 40% of the population believe? Or even 10%? It must be something clearly and demonstrably disproved that a large segment of the population believes because the media propagates the myth.