Kansas Senate 2026 — Marshall at 68%, the money on Hamilton

Kansas is the second-busiest single Senate race on either exchange, and the money is on the candidate who is losing. Kalshi turns $130,285 a day on Roger Marshall at 68% against the Democrat Adam Hamilton at 34%—and Hamilton's leg has taken $77,925 of that against Marshall's $52,360, on 517,506 contracts of open interest against Marshall's 280,689.

Polymarket says the same thing on a twentieth of the money. Marshall is 75% there, Hamilton 33%, and Hamilton's leg took $11,378 against Marshall's $8,206. Two venues, no shared order book, and the same inversion between price and flow.

The margin board is where the doubt actually lives. Marshall, 3+ points is priced at 50.0% and 5+ points at 46%—so a candidate the winner board treats as a two-to-one favourite is a coin flip to win by three. An eighteen-point gap between Kalshi and Polymarket's Republican legs, on a race neither venue thinks is close, is the second thing on this page worth explaining.

Kalshi's board on the left, Polymarket's on the right. Kalshi settles on certification in January 2027; Polymarket settles on election night, November 3. Manifold's party-level version sits further down beside the margin ladder.

Roger Marshall at 68% on Kalshi and 75% on Polymarket. Seven points of difference on the favourite leg between two venues that agree to within a point on most races in this catalog—and the thinner venue is the more confident one.

Adam Hamilton at 34% and 33%, carrying more money than the favourite on both venues. $77,925 against $52,360 on Kalshi, $11,378 against $8,206 on Polymarket, and 517,506 contracts of open interest against 280,689. This is the page.

The margin ladder on the left and Manifold's party-level board on the right. Kalshi prices Marshall, 3+ points at 50.0%, 5+ at 46% and 9+ at 21%—and the 9+ rung, at a fifth of a chance, is the busiest contract on the board at $1,004. A two-to-one favourite with an even-money three-point margin is a seat the market expects to be held narrowly.

Two boards that put Kansas next to its neighbours. The governor-senate combo has Republicans sweep at 64% on $2,520, with the split tickets at 17% and 9%. Beside it, Kalshi's direct head-to-head on which race lands closer: Kansas 53%, Nebraska 46%, on $3,962—the two highest-volume Senate books on the platform, priced against each other.

The general settles on certification in January 2027 on Kalshi and on election night, November 3, on Polymarket. The margin and combo boards settle with the result.

• 517,506 contracts on Hamilton at 34%. Nearly twice the paper behind a favourite priced at twice his odds. Either the challenger's backers are more committed than the price implies, or Marshall's holders took their positions long ago and stopped trading.
• Marshall at 68% on Kalshi against 75% on Polymarket. Seven points is a wide cross-exchange gap by this catalog's standards, and the deeper book is the cheaper one.
• The 3+ point margin leg at exactly 50.0%. The only genuinely two-sided contract on the page, and the one that decides whether this is a safe seat or a contest.
• The Kansas-versus-Nebraska board at 53/46. A direct bet on which of the two biggest Senate books ends up closer, priced almost even.
• Kansas at 6% on the closest-race board, behind Texas at 17% and Iowa at 13%. The national map does not yet believe the margin ladder.