Things are supposed to be looking rosy for Democrats this November. But in case Barack Obama loses the Presidency, an excuse is all ready to go: America's too racist to elect a black man. Not even, in his Vice Presidential pick Joe Biden's inimitable description, one so "articulate and bright and clean."

This narrative has gained traction with the Democratic Presidential candidate's recent setbacks in the polls. We hear it from the convention crowd in Denver and liberals in the press. The older, poorer, white, often Hillary...