He kept going after Huckabee but he never once went after McCain. Thompson is trying to draw support away from Huckabee, but isn't really trying to do the same for McCain. I think that if he doesn't win SC, he wants McCain to win it. If Huckabee and Thompson end up splitting a lot of the same voting base, then McCain will probably win in SC.
Thompson is friends with McCain. I think that if Thompson doesn't win SC, he's going to drop out and support McCain. He supported McCain in 2000 and was about to endorse McCain for 08 before the rumors started last spring that he was considering entering the nomination process.
It's vital that McCain's momentum gets stopped in Michigan.