Incumbent Sen. Lindsey Graham leads Polymarket trader consensus at 81% to win South Carolina's June 9 Republican Senate primary, bolstered by his commanding fundraising edge—over $19 million raised—Trump endorsement, and decades of name recognition despite polls like a March Pulse survey showing him at 41% amid a fragmented field. Challenger Mark Lynch holds second at 13.5% following Paul Dans' April 10 campaign exit and endorsement, which consolidated some anti-Graham support from the Project 2025 architect, while Dans lingers at 2.6% and Thomas Murphy trails at 0.2%. Though early polls signal runoff risk if no candidate exceeds 50%, traders price Graham's path-to-victory via incumbency advantages and momentum from recent filing-period consolidation.