2020 United States Senate election in South Dakota

The 2020 United States Senate election in South Dakota was held on November 3, 2020, to elect a member of the United States Senate to represent the State of South Dakota, concurrently with the 2020 U.S. presidential election, as well as other elections to the United States Senate, elections to the United States House of Representatives and various state and local elections. Incumbent Republican Senator Mike Rounds was reelected to a second term in office, overperforming Donald Trump in the concurrent presidential election by 4.93 points.

Nominee

 * Mike Rounds, incumbent U.S. senator

Eliminated in primary

 * Scyller Borglum, state representative

Results
[[File:South Dakota Senate Republican primary, 2020.svg|thumb|Results by county: {{legend|#E27F7F|Rounds}}

{{legend|#E27F7F|50–60%}}

{{legend|#D75D5D|60–70%}}

{{legend|#D72F30|70–80%}}

{{legend|#C21B18|80–90%}} {{legend|#FF9A50|Borglum}}

{{legend|#FF9A50|50–60%}} ]]

Nominee

 * Daniel Ahlers, former state representative and former state senator

Did not qualify

 * Clara Hart, board member of the Sioux Falls Arts Council

Declined

 * Erin Healy, state representative
 * Brendan Johnson, former United States Attorney for the District of South Dakota
 * Billie Sutton, former minority leader of the South Dakota Senate and nominee for Governor of South Dakota in 2018
 * Susan Wismer, state senator and Democratic nominee for Governor of South Dakota in 2014

Withdrew

 * Clayton Walker, independent candidate in the 2014 United States Senate election in South Dakota and Democratic candidate in the 2010 South Dakota House of Representatives elections

Results

 * Counties that flipped from Democratic to Republican
 * Clay (largest municipality: Vermillion)
 * Day (largest municipality: Webster)
 * Marshall (largest municipality: Britton)
 * Mellette (largest municipality: White River)
 * Roberts (largest municipality: Sisseton)