Nikki Gronli vs. Marty Jackley polls and 2026 forecast (South Dakota's at-large House seat)
Our forecast gives Marty Jackley (R) a >99% chance of winning (rating: Safe R), as of October 16, 2026. Expected margin: Jackley +17.5; in 80% of simulations the margin falls between Jackley +24.3 and Jackley +10.7. Polling average: Jackley +11.2 across 1 poll. Incumbent: Dusty Johnson. 2024 presidential result here: R+29.9.
House forecast · How the forecast works