Run Keyes. Whoever is put up against Obama at this point basically has no chance so it might as well be a real Republican. If nothing else he can make some points during the campaign.
Dr. Keyes at least has a network of conservatiev supporters from around the country who can help him. Dr. Barthwell doesn't have that.
And many of Keyes's friends are among the conservatives who have basically felt abandoned by the Republican Party, so he might help the party keep some of them in the tent.
Of course, the Maryland GOP basically turned its back on him when he ran for Senator in Maryland. Apparently, even to Maryland Republicans, no one is supposed to be that conservative -- especially a black guy.