Mike Rounds (R) has held this seat since 2015 and is running for re-election. Before that: Tim Johnson (D). The November field carries no Democratic candidate. Independent Brian Bengs is the principal challenger.
FTP Race SignalA composite of market, polling and money. The prediction-market price anchors it; a polling average moves it: the last 30 days, or the three most recent pollsters when fewer polled. Polls paid for by a candidate, party or allied group move 2 points toward the other side and count half. When the three most recent independent pollsters each have the race within three points, it is a Toss-up unless the market is already decisive. Fundraising counts only at a five-to-one gap. Past results are context, not inputs. A rating changes only when the evidence clears the line.
The market is less sure of this seat than its history is: a 31-point Republican hold in 2020, priced at 94¢ today.
Likely R
Safe ILikely ILean IToss-upLean RLikely RSafe R
Polling · Lean RRounds +5 (average of 3 pollsters Rounds +5, Sep 27).Market · Likely RR 94¢: traders' price for a Republican hold.Prior result · Safe RR+31.48 in 2020.PollsRounds +5MarketR 94¢2020 resultR+31.5
MarketR 94¢PollsRounds +52020R+31.5
Market and polls both favor Rounds.
Polling moved 3 points toward the Republican over 18 days.As of October 12.
Market
BandPRICEToss-up50¢ to 65¢Lean65¢ to 82¢Likely82¢ to 95¢Safe95¢ and above
BandPOINTSToss-up0 to 5Lean5 to 10Likely10 to 20Safe20 and above
Rounds +5
Zenith Polls ↗B+Sep 24 to 27 · n=500 LVRounds +6Bengs sponsorRounds +6 · Bengs sponsor · counts as Rounds +8 at half weight
PPP ↗BSep 8 to 9 · n=629 RVRounds +3Bengs sponsorRounds +3 · Bengs sponsor · counts as Rounds +5 at half weight
Impact Res. ↗BAug 13 to 17 · n=500 LVEVENBengs sponsorEVEN · Bengs sponsor · counts as Rounds +2 at half weight
Average of the latest poll from each of the 3 most recent pollsters; fewer than three polled in the last 30 days. Polls paid for by a candidate, party or allied group move 2 points toward the other side and count half.
Earlier polls · 2
Public Opinion Strategies (R) ↗July 6 to 9, 2026 · n=500 LVRounds +23Rounds sponsorRounds +23 · Rounds sponsor · counts as Rounds +21 at half weight
PPP ↗BMay 29 to 30 · n=726 RVRounds +4Bengs sponsorRounds +4 · Bengs sponsor · counts as Rounds +6 at half weight
Prior result
BandPOINTSToss-up0 to 5Lean5 to 12Likely12 to 25Safe25 and above
R+31.5
Mike Rounds (R)
65.7% to 34.3% · 2020 general election
def. Dan Ahlers (D). Margin verified against retrieved official results.
Total receipts in the 2025 to 2026 two-year cycle, through June 30, 2026; Rounds leads 4 to 1, short of the 5 to 1 at which fundraising takes a place on the spectrum.
The general election is on November 3, which is 22 days away.