Mike Rounds (R, Class 2) is up for re-election in 2026. John Thune (R, Class 3) — Senate Majority Leader — was re-elected in 2022 and is next up in 2028. Thune is NOT on the 2026 ballot.
- Mike Rounds (R, Class 2) seeks his third Senate term — first elected 2014, re-elected 2020. Race rated Safe Republican.
- Trump won South Dakota by 29.2 points in 2024 (63.4%–34.2%) — one of the most Republican-leaning states in the country.
- Rounds is a former South Dakota Governor (2003–2011) and has built a bipartisan reputation on veterans, banking, and rural issues.
- John Thune, as Senate Majority Leader, holds Class 3 — re-elected in 2022, next election 2028.
Key Facts — South Dakota Senate 2026
Historical Results — South Dakota Senate (Class 2)
Note: The 2002 entry shows the Class 2 seat changing from D (Johnson) to R (Thune). Rounds won the open Class 2 seat in 2014 after Tom Daschle’s long tenure ended and the seat moved Republican in 2002.
2026 Senate Context & National Landscape
While South Dakota has no competitive Senate race in 2026, the national Senate landscape is highly consequential. Democrats hold a narrow path to a Senate majority, requiring net gains in a map that favors Republicans. The Generic Ballot currently shows Democrats with a significant national advantage, but Senate maps often diverge from House dynamics due to state-specific factors.
Key competitive Senate races in 2026 include Georgia (Ossoff, D), Nevada (Rosen, D), Ohio (special election), Iowa (open seat), and Montana (Daines, R). The outcome of these races will determine Senate control through 2028. See the full Senate 2026 overview for all 33 Class 2 seats and current ratings.
National factors shaping all 2026 races include Trump's approval rating (currently at 38.1% approve, 59.2% disapprove), the economic outlook following Liberation Day tariffs, and immigration enforcement as a mobilizing issue for both base voters. The independent and swing voter bloc will be decisive in competitive states, while safe states like South Dakota are largely insulated from national wave dynamics.
Frequently Asked Questions
Who is running for Senate in South Dakota in 2026?
Mike Rounds (R, Class 2) is seeking his third Senate term. He was first elected in 2014 (open seat) and re-elected in 2020 by 26.7 points. Senate Majority Leader John Thune holds the Class 3 seat and is not up until 2028.
Is John Thune running for re-election in 2026?
No. Thune holds the Class 3 South Dakota Senate seat, re-elected in 2022 — his next election is 2028. The 2026 race is Mike Rounds's Class 2 seat.