In 2026, 70.5% of the state legislative incumbents running for election in South Dakota will face primary contests, a record high since 2010.
In total, 55 incumbents face contested primaries across the South Dakota House and Senate. The average number of incumbents contested each election cycle since 2010 was 24. All 55 of the contested incumbents are Republicans.
Republicans have a 32-3 majority in the Senate and a 65-5 majority in the House.
South Dakota has 50 contested state legislative primaries in 2026, also a record high since 2010. All but one of the primaries are for Republicans.
In total, 214 major party candidates—45 Democrats and 169 Republicans—filed to run. All of the state’s 70 House seats and all 35 Senate seats are up for election. Twenty-seven of those seats are open, meaning no incumbents filed. The average number of open seats each election year from 2010 to 2024 was 33.
South Dakota has had a Republican trifecta since the party gained control of the Senate in 1995. South Dakota’s state legislative primaries are scheduled for June 2.