There isn't anybody for him to endorse. The people closest to his views are Michelle Bachman (who won't actually say she WILL deport every single illegal in this country) and Mitt Romney (who will say absolutely anything you want to hear). Neither of them, are actually totally in line with his views.
He really doesn't have anyone that he can totally support.
Well now, let me see. Oh, I know! He could endorse the only conservative who is in the top tier, Herman Cain. I think those two would hit it off great.