SD Senate · 2026
Republicans are favored to win this seat
60% probability
Candidates
Independent challenger -- treated as the out-party candidate. No Democrat is on the ballot; the probability shown is Brian Bengs's chance of winning.
Last verified 2026-09-14.
Marion Michael Rounds is an American businessman and politician serving as the junior United States senator from South Dakota since 2015.
Open seat.
modeled from historical independent performance -- CAVEAT: Bengs' only prior statewide run (2022, 26.2% vs Thune, not Rounds) was as the Democratic nominee, not as an independent; used as an imperfect proxy for the model's prior-run-overperformance term
The percentage above is P(the independent candidate leads), not a Democratic win probability -- this race has no Democrat on the 2026 ballot. Small-sample model (n=11 historical races); wide confidence interval reflects that.
Why we think this
- This is an open seat with no incumbent on the ballot, which tends to make the race more competitive than a defended seat.
- Separately, current public mood in this state specifically is shifting strongly toward Republicans, on top of the structural baseline.
Model details -- coefficients, calibration, and the full technical decomposition.
Model independent-v1 · computed 2026-09-16