Susan Collins has held Maine's Senate seat since 1997 and is running for a sixth term. On October 19, 2026 prediction markets made her the underdog: Kalshi had Democrat Troy Jackson at 61%, up 3 points in a week, with Collins at about 41%. Polls have shown a close race leaning Jackson, and Maine's ranked-choice voting means the final result could take days to settle.
Snapshot, October 19, 2026
| Market | Price |
|---|---|
| Kalshi: Troy Jackson (D) wins | 61¢ |
| Kalshi: Susan Collins (R) wins | ~41¢ |
| Kalshi: Democrats win Senate control | 64.8¢ |
A dated snapshot; the live price is the one that counts.
How the race got here
- June 9 primary: Graham Platner won the Democratic nomination with 72.1%. Gov. Janet Mills, who had suspended her campaign but stayed on the ballot, took 19.3%.
- Platner withdraws: Platner later left the race.
- July 25 convention: Maine Democrats picked Troy Jackson as the replacement nominee, 566 to 5.
- Collins: unopposed in the Republican primary.
Polls
| Pollster | Dates | Jackson | Collins |
|---|---|---|---|
| Rasmussen Reports (R) | Sep 8–10 | 46% | 45% |
| YouGov | Sep 2–8 | 48% | 44% |
| SSRS | Aug 31–Sep 6 | 48% | 45% |
| Abacus Data | Aug 26–28 | 52% | 43% |
| Beacon (D) / Shaw & Co. (R) | Aug 6–10 | 48% | 46% |
The average across these is roughly Jackson 48%, Collins 45%. Collins has outrun her polls before, most famously in 2020, which is part of why the market price is 61% rather than higher.
Ranked-choice voting and settlement
Maine is the one Senate battleground that uses ranked-choice voting in the general election. If nobody clears 50% of first-choice votes, the last-place candidate is eliminated and those ballots move to their next choice, round by round. With an independent on the ballot, that is possible here. Both exchanges settle on the certified winner, so a close race may not pay out on election night. Read each contract's rules for the exact settlement source.
Trading it
Politics contracts carry a 4% taker rate on Polymarket and 7% on Kalshi, applied as rate × P × (1 − P); resting (maker) orders are free on both. Election markets are blocked on Kalshi in Washington and Nevada; see legality by state.
Sources: DefiRate Senate odds tracker (Kalshi, Oct 19, 2026); Wikipedia, 2026 United States Senate election in Maine (primary results, convention, polls). Not a recommendation.