Ohio Senate Special 2026

Ohio holds a Senate special election on November 3, 2026 to fill the seat JD Vance vacated. Jon Husted, appointed to it in January 2025, is defending against Sherrod Brown, who held the state's other seat for eighteen years before losing it in 2024. At roughly $324k in 24-hour volume, Kalshi's Ohio Senate winner? book is the second-deepest individual Senate race on the board.

The reason to watch it here is that the exchanges disagree about who is ahead. Kalshi prices Husted at 51.5% and Brown at 48.5%. Polymarket has it the other way round—Brown 51.5%, Husted 49.5%. Manifold splits the difference with Husted at 50.5%. Three venues, a three-point spread, and a sign flip in the middle of it: on a race this close, the cross-exchange disagreement is larger than either book's stated edge.

Kalshi carries the depth, Polymarket carries the contrarian sign, and Manifold is the independent third read. All three settle on the certified result of the same election, so the gaps between them are pure venue disagreement rather than differences in contract language.

The two candidate legs priced directly—and the volume split is the tell. Of Kalshi's $324k in 24-hour turnover, $271k sits on the Brown leg against $52k on Husted's. The favorite is the Republican; the flow is overwhelmingly on the Democrat. That is either conviction arriving ahead of the price or one side of the book simply being cheaper to express.

Two ways of asking how close this gets. The margin Cumulative prices a Republican win by 2+ points at 37.5% and by 6+ at just 15%. The Governor-Senate combo is deadlocked—an Acton/Brown Democratic sweep and a Ramaswamy/Husted Republican sweep are both at 39.5%, leaving about 22% on a split ticket. See also Ohio Governor 2026.

How this race sits against the rest of the cycle. The closest-race book ranks Ohio third at 11.5%, behind Texas at 15.5% and Iowa at 12%. The four-state tossup combo prices a Democratic sweep of Texas/Alaska/Iowa/Ohio at 34.5% against a Republican sweep at 33.5%—the whole tossup map is a coin flip, and Ohio is one of the four coins.

• The sign flip is the trade, if there is one. Kalshi says Husted, Polymarket says Brown, and the two are three points apart on a market that resolves identically. Watch whether they converge before Election Day or stay split—persistent disagreement on a deep book usually means different participant bases, not mispricing.
• Volume concentration on one leg. $271k of $324k on Brown against a price that has him behind. If the price follows the flow, that is the earliest signal in the stack.
• The margin ladder is doing the real work. A 51/49 winner book tells you almost nothing; the Cumulative saying 6+ points is only 15% tells you the market expects this decided inside a couple of points either way.
• Split-ticket risk. Ohio has voted for a Democratic senator and a Republican president in the same cycle before. The combo book's 22% on a split is the cleanest price on whether it happens again.
• Certification lag. Kalshi settles on the certified result in early January 2027, Polymarket on the November 3 outcome. In a race this close, the two could sit apart for weeks after the votes are counted.
• This is a special election. The winner serves the remainder of the term, and the seat is up again in 2028—SENATEOH-28 already lists, thinly.