By JOE HOLLEY and CARLA MARINUCCI

HOUSTON CHRONICLE

GOP presidential candidate Ron Paul, coming off a strong third-place finish in the Iowa caucuses, now charges into the New Hampshire primary with a feisty, combative strategy aimed at maximizing his appeal to voters in the “Live free or die” state whose independent outlook would seem to mirror his own political profile.

Paul has plunged into a verbal duel with Newt Gingrich, is preparing for two critical televised debates this weekend and has shown himself eager to take on the upstart, former Pennsylvania Sen. Rick Santorum, and the frontrunner, former Massachusetts Gov. Mitt Romney.

The question for the libertarian Texas congressman, as it always is when he runs nationwide, is whether he can build on the avid support of his core constituency and appeal to a broader electorate. That question will be answered shortly, not only in New Hampshire, but also in South Carolina and Florida, the three remaining early-voting states.

“He gets to about 15 percent wherever he runs,” said Dave Woodard, a Clemson University political scientist. “I think he has less of a ceiling here (in South Carolina) than he does in Iowa and New Hampshire, just because of the conservative Christian culture here.”

This time around, Paul has been a factor, in large part, because of his campaign capabilities. James Guth, a political scientist at Furman University in Greenville, S.C., said that early in the campaign Paul was the only candidate organizing and campaigning in South Carolina. “He has a grab-bag constituency here,” he said.

The Texas congressman isn’t resting on Iowa laurels. He continues to run hard, in South Carolina and elsewhere.

In the Palmetto State earlier this week, he made a six-figure advertising buy, touting his conservative bona fides to voters who may be skeptical about his isolationist views or his libertarian hands-off approach to such issues as abortion and gay marriage.

“South Carolina voters are receptive to Ron Paul’s message that life is precious and military service is honorable, all in the context of his overall philosophy of a return to personal and economic liberty,” said Jesse Benton, Paul’s national campaign chairman, announcing the ad buy.

Just hours after the close of the Iowa caucuses, Paul delivered a scathing retort to Gingrich, who labeled Paul’s foreign policy “dangerous.”

He called the former House speaker a “chicken” who, apparently, had no worries about danger to America when he took deferments rather than volunteering for military action in Vietnam. Paul caustically noted that politicians who send young people to war rather than going themselves are called “chicken hawks.”

Paul supporters downplay any suggestion that their candidate’s 21-percent take in the Iowa vote was a disappointment, especially given that this is the Texas congressman’s third try at the presidency.

“The campaign is talking about slow growth,’’ said John Dennis, a former California congressional candidate and a key organizer for Paul who served as a candidate surrogate in Iowa on caucus night. “People say Ron Paul can get only 21 percent and that’s it. They forget the base was 10 percent four months ago, and there’s very little attrition.”

Dennis said Paul’s aggressive retort to Gingrich was a reminder that his opponents in the race have to take him seriously.

“Romney has hit the ceiling. Gingrich has hit the ceiling,’’ he said. “And Santorum, frankly, in terms of the anti-Ron Paul candidacy, was the last bullet in the revolver.”

Santorum’s Iowa surge “came at a point where no one could point out what he’s done,’’ Dennis said. “That game is over. Mr. Santorum isn’t going to have the money to deal with what’s about to hit him.”

Chad Connelly, South Carolina’s Republican Party chairman, said he heard the story recently of a Paul supporter clinging precariously above an interstate highway as he hung a Ron Paul sign from the overpass.

“That’s the kind of passion every candidate would love to have,” Connelly said.

At the same time, Guth said, South Carolina “has a history of pragmatism. They like to decide the election. Paul’s going to be a factor, but he won’t win the primary.”

GOP consultant Rob Stutzman, a former Romney adviser, said that while Paul had an advantage in a caucus state, he is facing a new challenge in New Hampshire and South Carolina, especially with Romney’s powerful campaign structure and his friends mounting effective super PAC attacks on challengers.

Stutzman said the Paul voter bloc remains undefined, “kind of the Island of Misfit Toys.’’

“It’s people that feel disenfranchised across the entire political spectrum – and they splinter into a lot of places,’’ he said.

Dennis acknowledged that the debates this weekend likely will be crucial for the 76-year-old Texan.

“If he’s going to get bounce, he has to do well in these debates and start assuaging concern about his policies, especially in Iran,’’ he said. “It’s a complex problem – and there’s so much propaganda.”

joe.holley@chron.com

cmarinucci@sfchronicle.com