Will the Republican Party hold exactly 46 Senate seats after the 2026 midterm elections?

Research grade

⚖️ NeutralNo at 100%

No measured edge, which here means a loss: the plain consensus (5+ holders, 60 %+, held to resolution) lost −3.0 % a trade after costs out of sample in the full-year test (n 86,296, 95 % CI −3.6 to −2.4 %).

• ≤ Side priced over 95¢Full year, out of sample: 0.90–0.95 −0.2 % a trade (n 12,989, 95 % CI −0.6 to +0.3); above 95¢ little is left to win and the tests stop at 0.95.
• + Quality net +3 or moreNot confirmed. Oct 22 backtest: net +3 when the consensus formed made +7.2 % a trade (n 358), with 5 events giving two thirds of it. Full year, out of sample, the closest rule (3+ proven winners, two thirds on the side) lost −1.9 % a trade (n 49,161, 95 % CI −2.6 to −1.1).

The rules come from our Oct 22 2026 backtest (one entry per market, held to resolution, after a 1¢ half-spread and Polymarket's taker fees). Our full-year test without hindsight (Oct 26 2026) found none of them profitable out of sample, and the plain consensus lost −3.0 % a trade. The grade describes the market; it is not a forecast, not an edge and not advice.