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.

2020 United States Senate election in South Dakota

← 2014 November 3, 2020 2026 →

Nominee Mike Rounds Dan Ahlers Party Republican Democratic Popular vote 276,232 143,987 Percentage 65.74% 34.26%

County results Precinct results Rounds:      50–60%      60–70%      70–80%      80–90%      >90% Ahlers:      50–60%      60–70%      70–80%      80–90%      >90%

U.S. senator before election Mike Rounds Republican Elected U.S. Senator Mike Rounds Republican

Republican primary

Candidates

Nominee

• Mike Rounds, incumbent U.S. senator^[1]

Eliminated in primary

• Scyller Borglum, state representative^[2]

Results

Results by county:

  Rounds

•   50–60%
•   60–70%
•   70–80%
•   80–90%

  Borglum

•   50–60%

Republican primary results^[3]

Party		Candidate	Votes	%
	Republican	Mike Rounds (incumbent)	70,365	75.23%
	Republican	Scyller Borglum	23,164	24.77%
Total votes			93,529	100.00%

Democratic primary

Candidates

Nominee

• Daniel Ahlers, former state representative and former state senator^[4]

Did not qualify

• Clara Hart, board member of the Sioux Falls Arts Council^[5]

Declined

• Erin Healy, state representative^[6]
• Brendan Johnson, former United States Attorney for the District of South Dakota^[7]
• Billie Sutton, former minority leader of the South Dakota Senate and nominee for Governor of South Dakota in 2018^[8]
• Susan Wismer, state senator and Democratic nominee for Governor of South Dakota in 2014^[6]

Independents

Candidates

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^[9]

General election

Predictions

Source	Ranking	As of
The Cook Political Report[10]	Safe R	October 29, 2020
Inside Elections[11]	Safe R	October 28, 2020
Sabato's Crystal Ball[12]	Safe R	November 2, 2020
Daily Kos[13]	Safe R	October 30, 2020
Politico[14]	Safe R	November 2, 2020
RCP[15]	Safe R	October 23, 2020
DDHQ[16]	Safe R	November 3, 2020
538[17]	Safe R	November 2, 2020
Economist[18]	Safe R	November 2, 2020

Polling

Poll source	Date(s) administered	Sample size[a]	Margin of error	Mike Rounds (R)	Dan Ahlers (D)	Undecided
Nielson Brothers Polling[19]	October 24–28, 2020	479 (LV)	± 4.48%	56%	39%	5%

Results

United States Senate election in South Dakota, 2020^[20]

Party		Candidate	Votes	%	±%
	Republican	Mike Rounds (incumbent)	276,232	65.74%	+15.37%
	Democratic	Daniel Ahlers	143,987	34.26%	+4.75%
Total votes			420,219	100.00%
	Republican hold

By county

By county

County Mike Rounds Republican Daniel Ahlers Democratic Margin Total votes # % # % # % Aurora 1,002 71.32 403 28.68 599 42.63 1,405 Beadle 5,104 71.99 1,986 28.01 3,118 43.98 7,090 Bennett 729 62.52 437 37.48 292 25.04 1,166 Bon Homme 2,156 72.11 834 27.89 1,322 44.21 2,990 Brookings 8,792 60.48 5,746 39.52 3,046 20.95 14,538 Brown 11,168 64.00 6,283 36.00 4,885 27.99 17,451 Brule 1,735 69.65 756 30.35 979 39.30 2,491 Buffalo 223 40.92 322 59.08 -99 -18.16 545 Butte 3,809 79.85 961 20.15 2,848 59.71 4,770 Campbell 745 85.93 122 14.07 623 71.86 867 Charles Mix 2,542 66.88 1,259 33.12 1,283 33.75 3,801 Clark 1,397 75.64 450 24.36 947 51.27 1,847 Clay 2,857 50.44 2,807 49.56 50 0.88 5,664 Codington 9,479 72.33 3,626 27.67 5,853 44.66 13,105 Corson 681 53.88 583 46.12 98 7.75 1,264 Custer 3,973 72.82 1,483 27.18 2,490 45.64 5,456 Davison 5,893 69.88 2,540 30.12 3,353 39.76 8,433 Day 1,895 63.93 1,069 36.07 826 27.87 2,964 Deuel 1,714 73.18 628 26.81 1,086 46.37 2,342 Dewey 884 45.43 1,062 54.57 -178 -9.15 1,946 Douglas 1,469 86.21 235 13.79 1,234 72.42 1,704 Edmunds 1,539 77.45 448 22.55 1,091 54.91 1,987 Fall River 3,009 75.19 993 24.81 2,016 50.37 4,002 Faulk 975 82.07 213 17.93 762 64.14 1,188 Grant 2,723 72.63 1,026 27.37 1,697 45.26 3,749 Gregory 1,766 78.35 488 21.65 1,278 56.70 2,254 Haakon 1,032 90.69 106 9.31 926 81.37 1,138 Hamlin 2,413 78.60 657 21.40 1,756 57.20 3,070 Hand 1,480 79.66 378 20.34 1,102 59.31 1,858 Hanson 1,796 76.10 564 23.90 1,232 52.20 2,360 Harding 727 90.87 73 9.13 654 81.75 800 Hughes 6,217 70.95 2,546 29.05 3,671 41.89 8,763 Hutchinson 2,982 79.44 772 20.56 2,210 58.87 3,754 Hyde 568 79.89 143 20.11 425 59.78 711 Jackson 756 67.92 357 32.08 399 35.85 1,113 Jerauld 720 72.22 277 27.78 443 44.43 997 Jones 497 83.39 99 16.61 398 66.78 596 Kingsbury 1,970 70.89 809 29.11 1,161 41.78 2,779 Lake 3,816 64.84 2,069 35.16 1,747 29.69 5,885 Lawrence 9,385 68.29 4,358 31.71 5,027 36.58 13,743 Lincoln 21,221 65.83 11,013 34.17 10,208 31.67 32,234 Lyman 1,066 66.67 533 33.33 533 33.33 1,599 Marshall 1,334 61.00 853 39.00 481 22.00 2,187 McCook 2,072 71.28 835 28.72 1,237 42.55 2,907 McPherson 1,086 82.21 235 17.79 851 64.42 1,321 Meade 10,355 76.53 3,176 23.47 7,179 53.06 13,531 Mellette 468 60.70 303 39.30 165 21.40 771 Miner 807 70.42 339 29.58 468 40.84 1,146 Minnehaha 52,773 57.63 38,799 42.37 13,974 15.26 91,572 Moody 1,877 58.29 1,343 41.71 534 16.58 3,220 Oglala Lakota 510 15.93 2,691 84.07 -2,181 -68.14 3,201 Pennington 37,694 66.27 19,184 33.73 18,510 32.54 56,878 Perkins 1,395 84.85 249 15.15 1,146 69.71 1,644 Potter 1,160 83.82 224 16.18 936 67.63 1,384 Roberts 2,529 58.87 1,767 41.13 762 17.74 4,296 Sanborn 898 76.17 281 23.83 617 52.33 1,179 Spink 2,178 68.84 986 31.16 1,192 37.67 3,164 Stanley 1,274 77.12 378 22.88 896 54.24 1,652 Sully 759 81.88 168 18.12 591 63.75 927 Todd 706 28.22 1,796 71.78 -1,090 -43.56 2,502 Tripp 2,188 81.34 502 18.66 1,686 62.68 2,690 Turner 3,416 75.21 1,126 24.79 2,290 50.42 4,542 Union 6,364 72.56 2,407 27.44 3,957 45.12 8,771 Walworth 2,040 79.53 525 20.47 1,515 59.06 2,565 Yankton 6,994 64.51 3,848 35.49 3,146 29.02 10,842 Ziebach 450 49.56 458 50.44 -8 -0.88 908 Totals 276,232 65.74 143,987 34.26 132,245 31.47 420,219 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)

Notes

1. Key:
   A – all adults
   RV – registered voters
   LV – likely voters
   V – unclear