Al Sharpton on yesterday's Daily Show made pretty much the same point - - Cain was "blacker," being a Southern black and having no interracial parents.
However, he also said that he wouldn't vote for Cain if he were running against a white man, (when, presumably it would be easier to vote for Cain against a white than for Cain against Obama.) This drew a laugh, because it was obvious that Sharpton was partially kidding - - he'd obviously have to vote for Cain if the white man running against him were the Grand Dragon of the KKK.
He didn't feel Cain has a hope in hell of peeling off black votes from Obama for at least three things that Cain said early in his campaign, the first being that most blacks were brainwashed and ignorant, the next two being equally stupid and ugly, but I forget what they were. That 999 tax is starting to look dumber and dumber and it's hung like an albatross around Cain's neck. He's having a lot of trouble defending it in the debates and is starting to look stupid under pressure. But at this point I can't see him abandoning it without humiliating himself.