South Carolina voters head to the polls Tuesday for a high-stakes Republican special primary runoff to select a U.S. Senate nominee following the sudden death of four-term Sen. Lindsey Graham last month. The contest pairs interim Sen. Darline Graham—the late senator's sister—against U.S. Rep. Ralph Norman, in a race that serves as a direct barometer of President Donald Trump’s influence over the GOP base.
While political analysts and the latest polls point to a competitive finish driven by an abbreviated, three-week campaign, prediction markets like Kalshi reflect a clearer consensus on the expected outcome.
Kalshi Contract Prices Favor Darline Graham Over Ralph Norman
Trading activity on the prediction exchange Kalshi positions Darline Graham as the front-runner, pricing her probability of winning the Republican nomination at 67%. Shares backing Ralph Norman trail, hovering near 34% ahead of polls closing.
Graham’s market lead has remained resilient despite recent volatility. Her odds experienced a temporary drop following a debate where she candidly remarked that "national security is not my thing"—a notable point of contrast given her brother's long-standing focus on foreign affairs.
While Norman picked up momentum among local conservative groups following the slip, market movements remained bounded, keeping Graham in the lead.
Public Polling Data vs. Market Odds in South Carolina
In stark contrast to Kalshi's two-to-one margin, survey metrics and vote counts reveal a significantly narrower gap between the candidates:
- August 11 Primary Results: In the initial 10-candidate special primary, Graham finished first with 32.7% (109,582 votes) to Norman’s 24.6% (82,523 votes)—an 8-point gap that fell short of the 50% majority required to avoid a runoff.
- Public & Tracking Polls: Late-campaign tracking pollsters noted Graham’s lead narrowing in the days leading up to Election Day. While public polling generally held Graham slightly ahead, internal polling released by Norman’s campaign showed him leading Graham 52% to 40% among likely voters.
This divergence underlines the difference between market probabilities and polling numbers: while pollsters capture a tight electorate where turnout in a low-volume August runoff is notoriously difficult to project, Kalshi traders are heavily pricing in the power of institutional support and Trump's endorsement.
What Is at Stake for Donald Trump in SC
The South Carolina runoff carries broader national implications for President Donald Trump. Trump personally encouraged Graham to seek the seat, issued a primary endorsement, and headlined a rally in Myrtle Beach where he explicitly asked voters to "pretend as if I am on the ballot".
Federal Election Commission filings reveal substantial support from Trump-aligned political action committees, with the super PAC MAGA Inc. funneling $827,000 into text messaging and phone banking operations for Graham leading into the vote—one of the largest single-race expenditures during the midterm primary cycle.
A victory would shore up Trump’s endorsement track record following a series of high-profile primary defeats, whereas a Norman upset would demonstrate continuing resistance from local conservative bases against presidential endorsements.
