CalledUnofficial results
South Dakota Legislative District 18
South Dakota State Senate · South Dakota
Lauren Nelson won re-election by 15.3 points over Kay Swihart.
Lauren NelsonRepublican · winner · incumbent
57.7%4,485
Kay SwihartDemocrat
42.3%3,294
7,779 votes
Source: South Dakota Secretary of State unofficial resultsUpdated Nov 7, 2026, 1:22 PM ET
Where the race moved
Against the 2024 presidential vote
The seat's recent races
Source: Past results: 99chambers results archive (MEDSL, Klarner, state election offices)
Money in this race
Each line compares the two campaigns on one scale.
Kay SwihartLauren Nelson
$3.2K
Raised by the campaign
$40.5K
$1.8K
Spent by the campaign
$40K
$1.5K
Cash on hand
$860
Campaign money: South Dakota Secretary of State, through Oct 20, 2026.
Source: South Dakota Secretary of State campaign filingsUpdated Oct 20, 2026
Pre-election forecast (final, Nov 3)
Our model's last run before Election Day, Nov 3, 2026. It no longer updates.
- Kay Swihart
- 1%
- Lauren Nelson
- 99%
- Projected margin
- R+17.4