Poll Shows Lindsey Graham at 56% in South Carolina GOP Senate Primary, 23% Undecided

A new InsiderAdvantage poll conducted May 13–14, 2026 among 800 likely voters shows Republican Senator Lindsey Graham of South Carolina leading the state's GOP Senate primary with 56 percent support. Mark Lynch received 13 percent, Calvin Cowen 3 percent, Darius Mitchell 2 percent, Thomas Dismukes 2 percent and Pat Herrmann 1 percent. Twenty-three percent of respondents were undecided.

46 percentage points. Pollster Matt Towery stated that Lindsey Graham leads among every single demographic group. More than 60 percent of respondents in the InsiderAdvantage poll said Trump’s endorsement would help secure Graham’s victory.

South Carolina Republicans will vote in the primary on June 9, 2026. A candidate needs more than 50 percent in the South Carolina Republican primary to avoid a June 23 runoff. The survey marks the latest in a series showing Graham well ahead.

1 percentage points, showed Lindsey Graham at 41 percent, Mark Lynch at 21 percent, and Dans at 11 percent, with 22 percent undecided. Newsweek reported that earlier surveys followed a similar pattern.

5 percent, showed him at 48 percent. 6 million in cash on hand as of March 31, 2026, according to campaign finance reports.

Inside Elections rated the South Carolina Senate race as “Likely Republican” as of April 23, 2026. ” Sabato’s Crystal Ball places the South Carolina Senate race in the “Safe Republican” column. The Republican nominee will face the Democratic candidate in the November 3 general election.

Graham enters the 2026 cycle in a position of strength, with the state’s strong Republican lean delivering consistent double-digit GOP margins in federal races. His position has been reinforced by President Donald Trump’s endorsement.