South Dakota’s at-large House seat remains an open contest after incumbent Dusty Johnson pursued the governorship, yet the district’s R+15 partisan lean and consistent Republican dominance since 2008 underpin trader consensus favoring Marty Jackley. Jackley secured the GOP nomination with nearly 80 percent in the June primary and maintains a substantial fundraising edge exceeding $1.4 million. All major forecasters rate the race Solid or Safe Republican. Democratic nominee Nikki Gronli, a former USDA official, faces structural headwinds in a state where the party has not won the seat in nearly two decades. Late developments such as a major scandal or unforeseen national swing could still shift probabilities before November 3, though none have materialized to narrow the gap.