South Dakota’s at-large House seat remains a strong Republican hold in a state where the party has consistently won by wide margins, including 72 percent in 2024. The June 2 primary solidified Marty Jackley as the nominee after he defeated his main challenger by roughly 80 percent to 20 percent, backed by Trump endorsement and broad party support. Democrat Nicole Gronli faces the general election with limited resources and no recent polling showing competitiveness. Traders price the Republican outcome at 93.5 percent because historical results, primary consolidation, and structural partisan advantage create few realistic paths for an upset. A major scandal involving Jackley, unusually high Democratic turnout, or a national political shift could narrow the gap, though such developments remain uncommon in this district.