U.S. Senate in South Dakota
U.S. Senate · South Dakota
Mike Rounds won re-election by 21.0 points over Brian Bengs.
Source: South Dakota Secretary of State unofficial resultsUpdated Nov 7, 2026, 1:22 PM ET
Where the race moved
Against the 2024 presidential vote
Every county, 2024 to 2026
Each dot is a county, sized by votes cast and colored by who carried it in 2026. Dots above the line moved toward Bengs compared with the 2024 presidential vote; 55 of 65 did. The largest shift among the bigger counties: Fall River, +13.6 points.
Source: civicAPI county results (unofficial); 2024 president: MEDSL precinct returnsUpdated Nov 7, 2026, 1:34 PM ET
The seat's recent races
Source: Past results: 99chambers results archive (MEDSL, Klarner, state election offices)
By county
Show 57 more
Bar: share of the state's vote. Shift: change in margin from the 2024 presidential vote, + toward Democrats.
Source: civicAPI county results (unofficial); 2024 president: MEDSL precinct returnsUpdated Nov 7, 2026, 1:34 PM ET
Money in this race
Each line compares the two sides on one scale: their campaigns, and outside groups spending for them or against their opponent.
Top funders
Outside groups and direct contributors, ranked by what they put in; the color shows which candidate it helps.
| SOUTH DAKOTA CONSERVATIVE PACFor Rounds, against Bengs | $1.1M | |
| Retire Career PoliticiansFor Bengs, against Rounds | $1.1M | |
| Freedom from PoliticsAgainst Rounds | $772.7K | |
| DEFEND AMERICAN JOBSFor Rounds | $411.7K | |
| AMERICAN MISSIONFor Rounds | $229.7K | |
| Great Plains Voices PACFor Bengs, against Rounds | $100K | |
| BISON PACFor Bengs | $46.3K | |
| United Independents Campaign FundFor Bengs | $16K | |
| FORWARD PARTY VICTORY FUND INCFor Bengs | $12K | |
| VoteVetsFor Bengs | $201 |
Show 2 more
Campaign money: FEC, through Oct 14, 2026. Outside spending: independent expenditures by super PACs, parties and other groups, primary and general, as reported to the FEC through Nov 1, 2026, updated Nov 3, 2026. It leaves out spending not reported as independent expenditures (most issue ads and much dark money), so it understates all outside money.
Source: FEC campaign filings; FEC independent expendituresUpdated Nov 3, 2026, 1:05 AM ET
Polls against the result
The final average had Rounds ahead by 10.0. Rounds won by 21.0: a 11.0-point miss toward Democrats.
- Poll with Bengs ahead
- Poll with Rounds ahead
- Final polling average
- Result
| Pollster | Dates | Sample | Bengs | Rounds | Margin | Adjusted | Miss vs result | Grade | Release |
|---|---|---|---|---|---|---|---|---|---|
| Concord Public Opinion Partners for Education Reform Now AdvocacyD-sponsored | Oct 22–Oct 26 | 448 LV | 43 | 41 | D+2 | R+5.4 | +23.0 | B− | concordpublicopinionpartners.org ↗ |
| Emerson College for KELO-TV | Oct 19–Oct 21 | 803 LV | 46 | 54 | R+8 | R+7.3 | +13.0 | A+ | keloland.com ↗ |
| Quantus Insights | Oct 17–Oct 19 | 657 LV | 37.3 | 59.4 | R+22.1 | R+20.2 | −1.1 | — | semafor.com ↗ |
| Public Opinion Strategies for Mike Rounds's campaignR-sponsored | Oct 12–Oct 16 | 500 LV | 37 | 54 | R+17 | R+10.8 | +4.0 | B | x.com ↗ |
| Mason-Dixon Polling & Research, Inc. for Chiesman Center for Democracy at the University of South Dakota, South Dakota News Watch | Oct 12–Oct 14 | 500 LV | 37.4 | 56.4 | R+19 | R+18.2 | +2.0 | A | sdnewswatch.org ↗ |
| Concord Public Opinion Partners for Education Reform Now AdvocacyD-sponsored | Oct 6–Oct 8 | 400 LV | 43 | 42 | D+1 | R+6.4 | +22.0 | B− | documentcloud.org ↗ |
| Zenith Research for Brian Bengs's campaign | Sep 24–Sep 27 | 500 LV | 47 | 53 | R+6 | — | +15.0 | — | drive.google.com ↗ |
| Public Policy Polling for Brian Bengs's campaign | Sep 8–Sep 9 | 629 RV | 42 | 45 | R+3 | — | +18.0 | B+ | x.com ↗ |
| Lake Research Partners for Nikki Gronli's campaignD-sponsored | Aug 26–Aug 30 | 500 LV | 51 | 41 | D+10 | — | +31.0 | B+ | x.com ↗ |
| Impact Research for Brian Bengs's campaign | Aug 13–Aug 17 | 500 LV | 44 | 44 | Even | — | +21.0 | C | documentcloud.org ↗ |
| Public Opinion Strategies for National Republican Senatorial CommitteeR-sponsored | Jul 6–Jul 9 | 500 LV | 33 | 56 | R+23 | — | −2.0 | B | townhall.com ↗ |
| Public Policy Polling for Brian Bengs's campaign | May 29–May 30 | 726 RV | 40 | 44 | R+4 | — | +17.0 | B+ | hub.nationaljournal.com ↗ |
| Public Policy Polling for Brian Bengs's campaign | Feb 17–Feb 18 | 685 RV | 35 | 47 | R+12 | — | +9.0 | B+ | hub.nationaljournal.com ↗ |
| Public Policy Polling for Brian Bengs's campaign | Nov 13–Nov 14 | 814 RV | 31 | 44 | R+13 | — | +8.0 | B+ | hub.nationaljournal.com ↗ |
| Public Policy Polling for Brian Bengs's campaign | Jul 30–Jul 31 | 552 RV | 28 | 41 | R+13 | — | +8.0 | B+ | x.com ↗ |
Adjusted: after correcting for the pollster's house effect and likely-voter screens. Miss: the poll's margin minus the result; + means the poll leaned Democratic. Grade: the pollster's accuracy in past elections, A+ to D (pollster ratings).
Source: Each poll's release, via The New York Times and Wikipedia poll listsUpdated Oct 26, 2026
Pre-election forecast (final, Nov 3)
Our model's last run before Election Day, Nov 3, 2026. It no longer updates.
- Brian Bengs
- 4%
- Mike Rounds
- 96%
- Projected margin
- R+11.7
The candidates
Also on this ballot here
| Governor | R+27.0 |
| Attorney General | Unopposed |
| Secretary of State | R+22.3 |
| Treasurer | R+24.9 |
| Auditor | R+25.1 |
Results within this state. Source: Results and race calls: South Dakota Secretary of State (unofficial)Updated Nov 7, 2026, 1:22 PM ET