The most recent poll in South Carolina has Mitt Romney moving ahead of the pack.
Romney: 29%
Giuliani: 23
McCain: 13
Undecided: 12
Thompson: 10
Huckabee: 5
Paul: 4
If Romney can genuinely appeal to primary voters in South Carolina, and the South in general, I think he's the front runner to win the Republican nomination.
Romney has, far and away, run the best campaign to dislodge Giuliani from the #1 spot. He's winning in Iowa by double-digits (though Huckabee is surging). He's got just under a double-digit lead in New Hampshire. He's been winning in some Nevada polls but those have been very volatile. Among the early states, he seems to be doing meekly (a distant 3rd) only in Florida. But, Florida is the last of the early state voting.
It sometimes seems that only Romney is using the obvious tried and true strategy of winning in Iowa and New Hampshire and then using those victories to build a larger base. Giuliani seems to think he can be a national candidate without winning early. Thompson is floundering with some Southern strategy that won't get started until nearly a month after the earliest states vote. McCain gets solid national numbers but doesn't seem to be doing good in any specific state. Huckabee is just a longshot who's appealing to some base votes. Paul, of course, wins only the internet voting delegates.