That’s the case according to a Field Corporation Poll released January 26, 2010. In addition to that hard core 11% who say they don’t believe Obama was born in the USA, another 22% aren’t sure.
Eighty-five percent of Democrats, but just 42% of Republicans, maintain that Obama was born in the U.S. There is also a wide divergence of opinion between liberals, 96% of whom believe Obama was born in America, and conservatives, of whom fewer than half feel this way (45%). …
Just 29% of the voters who say they identify a lot with the tea party movement believe that Obama is a U.S.-born citizen.
In 2008, there were about 17 million registered voters in California, so by extrapolation we find there about 1.9 million birthers in California (not counting those unsure and those not registered to vote).