Interesting commentary from Powerline.
A Mason-Dixon poll of likely Republican primary voters in South Carolina shows Fred Thompson in the lead with 25 percent, followed by Rudy Giulinai (21 percent), Mitt Romney (11 percent), and John McCain (7 percent). Thompson's showing isn't all that significant -- if he can't outpoll two centrists and a yankee Mormon in South Carolina, he has no shot. The significance of this poll (unless it's an outlier) is McCain's dreadful showing of 7 percent. Polls taken a month ago (albeit by different organizations) showed him with two to three times that level of support (I discount the results of the American Research Group, which always seems to tilt heavily in McCain's favor).
Giuliani and Romney seem to be holding steady in South Carolina. What's changing is the Thompson-McCain split. An Insider Advantage poll from late May had McCain at 17 percent and Thomsson at 13 percent. The Mason-Dixon poll shows the combined Thompson-McCain support at essentially the same level, but with Thompson claiming about 70 percent of it.
It may be that the only thing standing between a two-man race between Giuliani and Thompson is Mitt Romney.
UPDATE: On the Democratic side, it's John Edwards who gets the bad news. In the state where he was born, he receives about half the support of Hillary Clinton and about one-third of Barack Obama's level.