It’s true that surveys indicate that gay marriage is wildly popular among DC whites and moderately unpopular among DC blacks, but I think it’s a bit misleading to really see this as a “racial divide.” Nobody would be surprised to learn about a community where college educated people had substantially more left-wing views on gay rights than did working class people. And it just happens to be the case that there are hardly any working class white people living in DC. Meanwhile, with a 34-48 pro-con split it’s hardly as if black Washington stands uniformly in opposition—there’s a division of views reflecting the diverse nature of the city’s black population.
At the end of the day “the city as a whole supported same-sex marriage by 54 percent to 34 percent” so the issue is going to come down to a clash between the desires of the city’s population and the desire of congressional conservatives to screw around with the District. And my guess is that having a ton of right-wing southern white guys talk about how DC shouldn’t be allowed to make its own rules in this regard isn’t actually going to endear the conservative movement to working class African-Americans in DC.