Rep. Julia Letlow commands 72% implied probability as the frontrunner in the Louisiana Republican Senate primary, driven by her incumbency in the U.S. House, superior early fundraising exceeding $2 million in initial reports, and favorable internal polling showing double-digit leads among GOP voters following incumbent Sen. Bill Cassidy's signals of a potential retirement. State Treasurer John Fleming holds 18% on statewide name recognition from his executive role and past congressional service, while Cassidy lingers at 11% amid uncertainty over his re-election bid. Traders' consensus reflects Letlow's path-to-victory through key endorsements and swing district strength ahead of the October 2026 jungle primary, with candidate filings and debates as upcoming catalysts.