Darline Graham, Ralph Norman battle to replace Lindsey Graham on ballot in South Carolina runoff

The power of President Donald Trump's endorsement and the legacy of the late Sen. Lindsey Graham are on the ballot in South Carolina, as voters go to the polls Tuesday in a special primary runoff election.

Facing off are Lindsey Graham's sister, Sen. Darline Graham -- a political newcomer who was first appointed to the seat to finish out the rest of Lindsey Graham's term -- and Rep. Ralph Norman, a staunch conservative and member of the hard line Freedom Caucus. Whoever wins the runoff will face Democratic candidate Annie Andrews in November.

Graham has framed her outsider status as an asset, while pointing to Trump's support as one of the key reasons conservatives should support her bid for a full term. And Trump threw more than just a social media endorsement behind her: he flew to Myrtle Beach for a rally on Friday, in one of his first major campaign stops during the 2026 midterms.

"Now, the critics say I shouldn't run for the Senate. They say I'm not a politician. You know what I say? Guilty as charged," Graham said during the rally to cheers. "And by the way, President Trump had never served in an elected office before, and I think he's done a damn good job."

Trump, later on, effusively praised Graham, saying "she only knows how to put America first."

Norman, meanwhile, has said that his experience is his "resume" and that conservatives in the Palmetto State can trust him more than a relative unknown like Graham.

"The establishment has already picked their candidate. Same old playbook, same old insiders. I'm not their choice. And this election is not for sale," he said in a campaign ad.

He has also questioned why Trump has gotten involved in the race in GOP-favoring South Carolina instead of focusing on ones where the GOP faces an uphill battle against Democrats. The White House, asked about some of Norman's comments about Trump, pointed to Trump's previous social media posts where he endorsed Graham.

Graham, on her end, has faced scrutiny from many fellow Republicans over her lack of political experience and occasional missteps on the trail.

During a one-on-one debate she had with Norman last Tuesday, she was asked if Taiwan and the South China Sea are national security issues for the United States. She answered, "I'm not that informed on national security. But I do support the military ... I'm not a polished politician up here. National security is not my thing, not my area of expertise, but I do support the military."

The comment, which contrasted with her brother's major focus on national security, sparked criticism from Norman's allies, including former Gov. Nikki Haley.

"Lindsey Graham was well informed on the United States' national security. Darline Graham admits she's not. This is not something you inherit. And it's critical in the U.S. Senate," Haley wrote on X last week.

Norman, in an interview with local outlet WHNS posted on Thursday, called Graham's answer "surprising" and hammered her for her lack of experience:. "There's no more important issue than national security ... there's no time for training on the job," he said.

But Graham, while admitting she feels she got the answer wrong -- telling Fox News she "tripped up on one question" -- told voters at an event last week, "To me, as I've walked around this room and I've asked people, 'Are y'all concerned about Taiwan?' You know what they said? No, they're concerned about the price of groceries, the price of gas, rising healthcare costs."

She also said she believes national security is important and she will become more informed about it. "Everybody has a first day on the job. President Trump -- was he a politician [when he was first elected]? Has he done a good job? Yes, he has," she told attendees.

David Woodard, a political scientist who also managed some of Lindsey Graham's early congressional campaigns, but is not working on this Senate race, told ABC News that he expects relatively low turnout and that those showing up to vote in such an off-cycle election are likely among the most opinionated, plugged-in Republicans.

"I think on the first round, people I was talking to had sympathy for Darline, thought it was great she'd serve out Lindsey's term," he said, adding that some of them now "think that Ralph Norman has credibility on issues that Darline lacks."

But some voters said they find Trump's endorsement of her, as well as her focus on the economy, a strong selling point.

Mike Funderburk, a contractor from Neeses, South Carolina, who voted early for Graham, said the economy is his top issue.

"I think she's probably going to have a steep learning curve," he said. "But I'm willing to give her the benefit of the doubt."

ABC News' Michelle Stoddart contributed to this report.