If the new Insider Advantage poll of 720 likely South Carolina voters taken yesterday holds up, Mitt Romney appears to have picked up momentum even before the news broke of Jon Huntsman’s withdrawal from the race.  Romney now has a double-digit lead over Newt Gingrich, 31.9% to 20.8%, with Ron Paul and Rick Santorum within a point of each other for third place, at 14.2% and 13.2% respectively.    That’s the widest gap found yet in January polling for the Palmetto state, and moves the RCP average to give Romney nearly an eight-point lead in the race, as well as his first over-30% finish for the state.

Interestingly, Paul and Santorum tie for first among 18-29 year olds in the state (27.2%) each, with Huntsman third at 20.7% and Romney fourth at 16.9%.  Gingrich gets no votes among this demographic.  Otherwise, Romney sweeps the other age demos, wins both men and women, and both Republicans (by 10 points over Gingrich) and independents (by 8.5 points over Paul).  Paul wins 58.6% of the Democrats in the poll, which comprise about 5% of the sample.

For those hoping for a Rick Perry renaissance, there is little evidence to be found for one.  He actually trails Huntsman (6.2%) in this for last place at 4.6%.  Perry only scored significantly among black voters, winning 36% of the 22 included in the poll.  Otherwise, his most significant share of any demographic in this poll is his 7.1% among seniors, which puts him a very distant fourth behind Romney’s 42.1% control of this group.

Even so, Perry is still promising to campaign in Florida:

Texas Gov. Rick Perry brushed off the choice of over 150 Evangelical leaders and conservative activists to endorse Rick Santorum on Saturday after meeting in the governor’s backyard and proclaimed that he intends to continue his campaign on to Florida, even if he places last in South Carolina.

“You’re not going to get everybody to love you,” he said on CNN’s State of the Union on Sunday.

Though the group said they agreed with Perry on the issues, they didn’t think he was electable. Perry countered on Sunday, citing Ronald Reagan’s win in South Carolina in 1980 as evidence that he remains competitive in the race, despite having finished fifth and sixth in Iowa and New Hampshire, respectively.

Perry added that no matter what happens in South Carolina, he intends to compete in Florida in February.

Perry may still have the money to compete after South Carolina, but it would be hard to see the point in doing so.  His continued presence splits the conservative vote further, although at these levels of support, not by a whole lot. Rick Santorum would love to get those voters in order to vault past Ron Paul and start challenging Newt Gingrich, but that won’t happen if Perry digs in his heels.  However, this is almost certainly an example of final-week bravado.  A last-place finish here will provoke the same impulse as Perry’s fifth-place finish in Iowa did — and this time, Perry will have to follow through on it.