From the outset of his campaign, Barack Obama has had to deal with doubts about his loyalty to African Americans. Skeptics point to his ancestry (his mother was white), his upbringing (he was raised in Hawaii, far afield from a cohesive black community) and, most of all, his large cadre of enthusiastic white supporters.
Obama appeals to white voters because of his eloquent optimism and gentle charisma but also because whites contrast him favorably with black leaders who are perceived as incessantly focusing on racism. A problem, though, is that strong white support in and of itself is enough to trigger...