I think Cain could deliver surprising numbers of blacks in Detroit. The democrat mayor of Detroit is a lot more ideologically similar to Cain than he is to Obama. Both are successful black businessmen.
The simple fact is that Detroit isn’t going to vote for a white man but they might just vote for a black man who could do them (and us) some real good.
One line of attack--why wasn't he a civil rights activist back in the 1960s?