As much as getting a bunch of "ZOMG BLACK PRESIDANT" rabble roused ghetto trash to vote for him would be beneficial (they'd vote for him anyway, even if he was a white male ex-clan member, they always vote democrat), the last thing Barak wants is to whip up a "OMG U R NOT VOTING FOR HIM CAUSE HE IS BLACK" vs "OMG U R ONLY VOTING FOR HIM CAUSE HE IS BLACK" because the majority of the population don't care about race bullshit and will see his presidency as a load of bullshit if race is the major issue of his campaign. The Democrats are aware of this and may choose Hillary over him if he doesn't give some sort of assurance that racism will be kept to a minimum.