-Paul is following a formula similar to what helped him to strong finishes in Iowa and New Hampshire: doing well with non-Republicans and young people. Among actual Republicans in South Carolina he's at only 12%. But the state has an open primary and with Democrats and independents planning to vote in it he leads with 24% to 22% for Romney, 17% for Huntsman, and 11% for Gingrich. We're only projecting non-Republicans at about 20% of the electorate for South Carolina, but if Paul can bring that share up his prospects will improve.
Paul is also running near even with voters under 45, getting 25% to Romney's 27% with Gingrich at 20% and Santorum at 13%. He does quite poorly with voters over 45, getting just 10%, but if he's able to draw out a younger electorate than the state typically sees his momentum may continue.