South Dakota at-large

Marty Jackley (R) vs Nikki Gronli (D).

Count in progress (28% of the expected vote): Marty Jackley (R) 67.7%; Nikki Gronli (D) 32.3%. Source: The Associated Press.

Cook: Solid R. Public polls: 0.

Atlas pre-election model — built only from data frozen on October 29, 2026; first published November 3 after polls closed, so it is a test of the method, not a prediction. Republican chance in that model: 100%.