U.S. Senate · All South Dakota races

South Dakota

Solid R

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Brian Bengs

Independent

1 in 100

chance of winning, out of 100

Mike Rounds

Republican · incumbent

99 in 100

Mike Rounds wins in 99 of 100 simulations.

There are no qualifying public polls yet, so the forecast leans on fundamentals; partisan lean, the national environment and incumbency point to Mike Rounds +27.2.

Where the result could land

Every simulated outcome, grouped in 2-point steps. Projected margin Rounds +27.2; 80 in 100 fall between Rounds +41.6 and Rounds +12.9.

The candidates

Brian Bengs

Independent

Raised

$1.7M

Cash on hand

$146K

Through 2026-09-30

No biography on file yet.

Mike RoundsIncumbent

Republican · American businessman and politician (born 1954)

Marion Michael Rounds is an American businessman and politician serving as the junior United States senator from South Dakota since 2015. A member of the Republican Party, he served as the 31st governor of South Dakota from 2003 to 2011. Wikipedia

Raised

$5.0M

Cash on hand

$1.7M

Through 2026-09-30

Official website ↗

Ballot list and short bios from Wikipedia (CC BY-SA); websites from Wikidata; fundraising from the FEC (cycle-to-date, latest report).

What if this race flips? Try it in the map builder →

Polls

No public polls have tested Brian Bengs against Mike Rounds yet.

No polls of this matchup yet, so there is no polling average. The forecast relies on fundamentals.

Chance of winning over time

How this race’s odds have moved as polls and the national environment changed.

No change over the past 3 months

Out of 100. Today: Bengs 1, Rounds 99.

What’s driving the forecast

The model blends each estimate by how much to trust it right now. Polls get 0% of the weight, 15 days out.

Polling average (after adjustments)	—	no polls
Partisan lean (Cook PVI, 2026 lines)	R+15.0	roughly 30 points of margin vs. the nation
National environment	D+9.6	generic ballot + presidential approval
Incumbent’s track record	Rounds +2.6	In 2020 they ran 5.3 pts more Republican than the state’s lean predicted; half carries over (max 10)
Incumbency	Rounds +3.0	incumbent’s side
Fundamentals estimate	Rounds +27.2	±11 typical error
Expert ratings (average)	Rounds +18.7	used only in the “+ Expert ratings” version
Forecast	Rounds +27.2	±11.2 standard deviation, including 2.3 for movement before Election Day

All three versions

Polls only: Brian Bengs 1 in 100 (Solid R)
Polls + fundamentals: Brian Bengs 1 in 100 (Solid R)
Polls + fundamentals + experts: Brian Bengs <1 in 100 (Solid R)

Published ratings

Other forecasters’ ratings, as listed on Wikipedia. Shown for comparison; they feed only the “+ Expert ratings” version.

Cook: Solid RDDHQ: Safe RThe Economist: Likely RSplit Ticket/FPO: Likely RFox News: Solid RInside Elections: Solid RRCP: Solid RSabato: Safe RSilver Bulletin: Solid RSplit Ticket: Likely R

County map

Counties colored by the 2024 presidential vote; on election night this switches to the live count in this race.

Color shows the 2024 presidential margin in each county. Hover or tap a county for its numbers.

2024 results: Fox News 2024 county results, compiled by Tony McGovern (github.com/tonmcg/US_County_Level_Election_Results_08-24). Not authoritative.

Rules and notes

Brian Bengs is an independent. Seats won by independents who haven’t said which party they’d caucus with are counted separately in chamber control.
Last polls close at 8 pm and 9 pm Eastern.
Last election: 65.74% R
Incumbent renominated

Senate races, closest first · this is #21 of 35