Democrats hold an 81% implied probability of winning the Wisconsin State Senate in November 2026, while Republicans sit at 18.5%. The chamber currently stands at an 18-15 Republican majority, with 17 seats on the ballot. New legislative maps from the 2023 Clarke v. Wisconsin Elections Commission ruling have shifted several districts toward Democrats, creating opportunities in areas won by Democratic statewide candidates in 2024. Multiple Republican retirements in competitive open seats, including the 5th and 21st districts, have further tilted the landscape. Analysts rate the chamber as lean or likely Democratic for a flip, citing strong Democratic candidates in targeted races and the need for just a net gain of two seats. Upcoming general election results on November 3 will determine final control.