**Larry Rhoden and Toby Doeden advanced to South Dakota’s first Republican gubernatorial primary runoff on July 28 after the June 2 vote split the field, with Doeden at roughly 31 percent and Rhoden at 25 percent.** Johnson and Hansen, finishing third and fourth, were eliminated. Rhoden’s incumbency—gained when he succeeded Kristi Noem in 2025—provides name recognition and institutional backing, while Doeden positions himself as a business outsider focused on eliminating property taxes. Central issues include affordability and tax policy, with Rhoden backing a measure letting counties swap property taxes for a sales-tax option. The close trader-implied probabilities reflect uncertainty over how support from the eliminated candidates consolidates, regional turnout patterns, and whether endorsements, spending, or debate positioning will shift momentum before the runoff ballot.