Emory University political scientist Merle Black analyzes the Republican field, discussing whether Herman Cain is a legitimate Republican presidential contender, how he would fare against President Obama in the general election and if Rick Perry still has a chance to be the nominee.

Black, Emory's Asa Griggs Candler Professor of Politics and Government, is a renowned expert on national politics and the foremost authority on politics in the South. One the nation's most incisive commentators, Black is coauthor of "Divided America: The Ferocious Power Struggle in American Politics."