2026 midterm election odds: Polymarket prices a Democratic Congress sweep at 66.5 percent

The balance-of-power market for the 2026 midterms has settled into a clear Democratic-leaning shape with twelve days until polls close on November 3. As of 09:19 UTC Thursday, October 22, Polymarket's categorical "2026 Balance of Power" event prices a Democratic sweep of both chambers at 66.5 percent (last trade 0.67), per the platform's Gamma API. The Republicans-take-all arm is the notable outlier in the opposite direction: it prices at just 7.5 percent (last 0.08) yet carries the single largest 24-hour volume of any control contract on the event, $1.37 million.

The categorical structure makes the state of play legible. Polymarket's balance-of-power event lists five open combinations: Democratic Senate with Democratic House at 66.5 percent, Republican Senate with Democratic House at 24.5 percent, Republican Senate with Republican House at 7.5 percent, Democratic Senate with Republican House at 0.85 percent (last traded 0.009, on $118,470 of 24-hour volume and roughly $1.29 million in quoted liquidity), and a fifth, Other, arm at 0.15 percent. The five arms sum to 99.5 percent, half a point under a clean 100, a rounding artifact across contracts quoted to different precisions; the point is that the long-shot combinations are listed, open, traded contracts, not an unpriced residual, and the arms together span the full outcome space. Add it up and the venue is pricing near-certainty that Democrats hold the House next Congress, with Senate control the genuinely contested leg.

That House read is explicit in its own market. "Will the Democratic Party control the House after the 2026 Midterm elections" trades at 92.5 percent (last 0.93), with $3.83 million in quoted liquidity and $389,000 of volume in the last 24 hours. The Senate is folded into the balance-of-power arms, and the House read falls out of them: the three combinations that keep the House Democratic, the Democratic sweep at 66.5 percent, the Republican-Senate-and-Democratic-House split at 24.5 percent, and the Democratic-Senate-and-Republican-House arm at 0.85 percent, sum to 91.85 percent of the probability mass, against 92.5 percent on the standalone House contract. That 0.65-point gap now runs the other way, the arms settling just under the standalone read rather than above it, and it is worth flagging on a beat where control contracts are easy to quote loosely.

Related reading: Prediction markets show Democratic advantage in 2026 House race while Senate remains a tossup.

The volume story is where the market gets interesting, and it is a story about structure, not about which side a reader should back. The Republican-sweep contract trades at 7.5 percent, near the bottom of the board, and yet it did $1.37 million in 24-hour volume at the 09:19 UTC pull, more than twice the $558,843 that traded through the 66.5-percent Democratic-sweep favorite and roughly four times the $337,355 moved by the split arm. Money has been flowing into the long-shot arm even as its price has not moved off the floor, volume-heavy activity at a stable, low price rather than any measured repricing of fundamentals. The movement matters here: volume into a stable, low price indicates positioning flowing to one side, not information driving the mid, and on a quiet news week that distinction is the predictive-markets tell.

At the state level the closest Senate race to even is Iowa, where Polymarket prices a Republican win at 56.5 percent against 43.5 percent for a Democrat, a 13-point gap on roughly $29,646 of 24-hour volume. Kansas is the next-tightest, with Republicans at 62.5 percent against 37.5 for Democrats, then Maine, where a Democratic win trades at 65.5 percent against 34.5 for a Republican. Texas, where a Democratic win trades at 67.5 percent (last 0.68), is the fourth-tightest of the twelve tracked Senate races at a 35-point gap, and at roughly $795,794 of 24-hour volume it is the heaviest-tracked control race on the board. Beneath the state map, volume is a feature of the categorical frame: the sweep and split contracts move far more in 24 hours than any single state market, which is how the event is structured rather than a signal about any one seat.

Related reading: US Iran ceasefire odds: Polymarket prices the lull fading from 94.6% to 37.5%.

The timing context matters. Today, October 22, is six days from the October 28 FOMC decision and twelve from the midterms themselves. Prediction markets on the Fed path are a separate beat from the balance-of-power prices here, and this desk has covered the October and December hike-odds shifts separately this week. The midterm pricing is its own, elections-as-expectations read, and it has not been re-priced by anything in today's macro calendar, so the numbers above are a clean snapshot of the political-state market rather than a reaction to a rate print.

The venue note is structural. Kalshi's open event feed, checked at the same timestamp, shows no live Senate or House control contract for the 2026 election cycle, so the categorical balance-of-power pricing currently lives entirely on Polymarket. A reader comparing venues has only one venue's framework to reconcile against an election-night certified result, which is itself a liquidity caveat worth carrying into November 3, not an argument about which direction the count lands.

Related reading: October Fed Ladder Priced Near a Coin Flip While the CPI Strip Quietly Reprices.

Next on the dating calendar for this family of markets is the poll close and first certified results on the evening of November 3, with Polymarket's balance-of-power event set to resolve at 04:59 UTC on November 4. What gets priced into these contracts between FOMC on October 28 and the final weekend is the swing to watch, and today's snapshot is the baseline.

This content is for informational purposes only and does not constitute financial advice. Past performance is not indicative of future results. Consult a qualified financial advisor before making investment decisions. Odds and movement in prediction markets are reported as market expectations, never as a recommendation of any position, pick or side.