After reading more about him, McDonnell wouldn't be such a bad candidate. He has the image of a moderate, and he won by a huge margin in Virginia. He is giving the SOTU response, amazing that in such short time for any politician. Military service, long history of legislating, it's all there. The only catch is his thesis... that could be a detriment.
I don't think it would be much of an issue. He handled himself well during the campaign for Governor when it came our, and he doesn't come across as an extremist.