Hooray for Chris Matthews on Morning Joe today! He is exactly correct. The comment by Romney is racist. The entire "birther" thing is racist. If Herman Cain had made this comment, it would not be a joke, it would not mean anything. Nobody asks for Romney's birth certificate because he is a white guy. Maybe Romney is not a racist, but he is certainly willing to take advantage of the racist mindset.
The fact that he pals around with Donald Trump and makes comments like this means he will accept votes from racist people solely because he is a white guy. The "birther" thing, the Muslim thing are all racist.
But worse than being racist, they are lies. Romney knows racist people will accept lies about a black person, even if they know that they are lies. This is the lesson from "To Kill a Mockingbird." I suggest that Tom B. and the other commentators should read the book.