Now it is Mr. Obama, the presumptive Democratic nominee, who has a harmonious chorus of broadcast supporters addressing a vital part of his coalition, feeding and reflecting the excitement blacks have for his candidacy in general. Mr. Obama is getting support from white liberal talk radio hosts as well, but the backing he is getting from black radio hosts could be especially helpful to his campaign’s efforts to increase black turnout and raise historically low voter registration enough to change the math of presidential elections in battlegrounds and traditionally Republican states like this one. –The New York Times