@Merry Andrew,
Not advocating for the exclusion of blacks in 1950's-1960's TV shows, but I know for a fact there were a couple of blacks shown in crowd scenes on the Andy Griffith show. And not even in the later ones, but in the original black-and-white first 2 or 3 seasons.
Besides, I think these spots by "opie" might be effective - Andy Griffith's show and persona are still beloved across the south, so who's to say his favoring Obama might not be persuasive to some subconscious degree?