South Dakota's at-large House district remains a solidly Republican seat following the open contest after incumbent Dusty Johnson retired. Republican nominee Marty Jackley, who won his primary decisively, faces Democrat Nicole Gronli in the November 3 general election. All major forecasters rate the race safe or solid Republican, consistent with the state's voting patterns and the 44-point GOP margin in 2024. Trader consensus centers on a 20-25% Republican victory margin as the most probable outcome because historical results and structural factors point to comfortable but not landslide wins in this deep-red state. Limited recent general-election polling and uncertainty around turnout or national midterm effects keep probabilities distributed across nearby margin buckets, while a Democratic win stays a low-probability outlier.