Sen. Lindsey Graham (R-SC) holds a wide advantage over primary challenger Mark Lynch in the latest South Carolina Republican Senate primary survey, with the incumbent leading among every demographic group included in the survey.

A new InsiderAdvantage poll of likely Republican primary voters conducted May 13-14 shows Graham at 56 percent, Lynch at 13 percent, other candidates at 8 percent, and 23 percent with no opinion or undecided.

“Graham leads among every single demographic group, something I rarely, if ever see in a poll,” InsiderAdvantage pollster Matt Towery said. “In other questions we included in the full survey more than sixty percent of those surveyed believed that, because of President Trump’s endorsement of Graham, he would win the contest. The only job left for Graham is to make sure he turns his voters out.”

Trump renewed his support for Graham in April and criticized Lynch in a Truth Social post, writing that Graham was doing a “fantastic job” and that Lynch was a “LUNATIC” who supports Rep. Thomas Massie (R-KY), whom Trump called “perhaps the Worst Congressman in the History of our Country.” Trump also said Lynch “would be a DISASTER for the Republican Party,” while Graham “GETS THE JOB DONE,” and urged voters to “VOTE FOR LINDSEY ALL THE WAY.”

Lynch had previously argued in a May 2025 appearance on Breitbart News Saturday that Americans are “tired of Lindsey and the fake platform he runs on.” Lynch also said that while “Trump needs some things out of Lindsey,” Graham “still is resisting Trump and fighting him at every turn,” adding that “We love President Trump, but that endorsement won’t save him this time.”

A March poll provided exclusively to Breitbart News and conducted for the Lynch campaign by Pulse Opinion Research using Rasmussen Reports licensed methodology showed Graham leading Lynch 41 percent to 21 percent on an initial ballot, with Paul Dans at 11 percent and 22 percent unsure. But after respondents were given additional information about the candidates’ records, Lynch led Graham 34 percent to 23 percent, while Dans remained at 11 percent and 26 percent were unsure.

“I’ve polled quite a few races like this in the ’26 cycle and Lindsey Graham is one of the weakest incumbents I’ve seen,” Mark Mitchell of Rasmussen Reports said at the time. “Despite the name ID advantage, Mark Lynch takes a clear lead on the informed ballot. This is a huge opportunity.”