Lindsey Graham, South Carolina’s senior senator, is not a conservative kingmaker like his Palmetto State colleague, Sen. Jim DeMint. But the maverick lawmaker is a Beltway player on national security, a vocal member of the Armed Services committee. As the GOP presidential primary heats up, with candidates dropping by Charleston and Columbia, he hopes to use his perch to prod the field.

In a recent interview with National Review Online in his Capitol Hill office, Graham was frank in evaluating the race so far. Turning first to the frontrunners, he says Gov. Rick Perry is a strong Republican presidential contender, but needs to “prove that he is electable.” Many Republicans, he notes, have lingering questions about Perry’s statements on Social Security, vaccination policies, and foreign policy.

“No one is going to win the White House without having a commitment to Social Security,” Graham says. “[Perry] is right about it going broke, and I think his [USA Today] op-ed piece was good, but we need to reinforce the message that we see the value of Social Security.”

Graham says Perry’s policy to require young girls to receive HPV inoculations unless their parents opted out, in order to prevent cervical cancer, could also spell trouble for the Texan. “From Governor Perry’s point of view, he was trying to protect girls from cancer. Whether you agree with his decision or not, I have no doubt about his motivation,” he says. “But I don’t think the mandatory route is the one to go. . . . Making someone do that, I don’t like.”

Graham, a colonel in the Air Force reserves, expects Perry, an Air Force veteran who “speaks our language,” to generate enthusiasm in South Carolina. Still, in coming weeks, he would like to hear more from Perry, and all of the candidates, about the importance of Afghanistan. Perry’s remarks in a recent debate, where he said the U.S. should bring its troops home “soon,” startled Graham. “I’m a bit disappointed in our candidates,” he says.

Moving forward, Graham thinks an increased emphasis on foreign policy could help candidates in South Carolina, even if they are lagging in the polls. He hints that former Pennsylvania senator Rick Santorum, who has received little press attention, could generate some momentum by vigorously addressing the terrorism threat, at home and abroad. “On the national-security side, I think he’s got a very good, strong voice,” Graham says. “He’s doing the best job, by far, of talking about the America that leads, the America that is exceptional.”

“I’m not going to let the party become the party of isolationism,” Graham says. He points to Jon Huntsman, the former Utah governor who is actively campaigning in South Carolina, as an example of the position he finds unpalatable. “I don’t know what he’s up to,” Graham says, commenting on Huntsman’s call for a speedy drawdown.

“[Huntsman] is a good guy, a very accomplished man, a terrific résumé,” he continues. “My problem is on the national-security front.” Graham acknowledges that some Republicans are “war weary,” but cautions Hunstman that conservative primary voters “do not want to give the Taliban the ability to regenerate. Most South Carolinians understand that we are fighting the bastards over there so that we don’t have to fight them over here — and we’re winning.”

Of course, all of this nitpicking by a South Carolina senator, Graham chuckles, will be for naught if Republicans do not compete for the S.C. crown. He is worried that the primary, which for years has been a crucial stepping stone to the nomination, may be overlooked by Perry’s fellow frontrunner, Mitt Romney, who has not invested heavily in the state. “You’re making a huge mistake if you don’t play in our state,” Graham warns. “Governor Romney could do well in South Carolina. . . . But he has to get an organization.”

“The South Carolina electorate is conservative, but electability matters,” Graham says. “We have an unblemished record of picking the nominees since 1980. New Hampshire and Iowa are hit and miss. South Carolina has got it right every time. I want to continue that tradition.”