Salon's Alex Koppelman examines the bogus conspiracy theory that Barack Obama wasn't born in the U.S., and therefore cannot be President. As Pablo reported today, the Supreme Court has denied to hear this ridiculous case, but even if it did, and found that it was without a doubt baseless and juvenile, there would still be people out there who refuse to let it go.
By the same token, there are plenty of people out there who like to claim that Obama is not Black: either he is biracial (which is, by these analyses, categorically exclusive from Black) or he is "half-White," as White as he is Black.
These characterizations belie an American political maxim: Black men are not Presidents.
For those who pray over Drudge that Obama's birth certificate is false, Obama as a Black man is nonviable. But even for those supporters who emphasize his biraciality without acknowledging his self-identification, Obama as a Black man is nonviable. He might be "Black," but he's not "too Black"--all Black, or only Black.
The U.S. Census did not allow "biracial" or "multiracial" until the 2000 Census. Nuance in race and ethnicity has never been our country's strong point, try though we may to perpetuate the story of the "melting pot", and perhaps Obama has just proven too complicated for our reductive racial categories.
But there are plenty of people out there who just can't bring themselves to admit that a Black man is President--legitimately President, and legitimately Black.
UPDATE: Ta-Nehisi Coates examines a similar point.