Democrats hold an 82% implied probability of winning control of the Wisconsin State Senate in the November 3, 2026 election, with Republicans at 15.5%. Republicans currently hold an 18-15 majority, and Democrats need a net gain of two seats among the 17 odd-numbered districts on the ballot. Recent forecaster updates, including Sabato’s Crystal Ball shifting the chamber to Lean Democratic on October 16, reflect new court-ordered maps signed in 2024 that improve Democratic positioning relative to prior lines, combined with six Republican retirements in competitive districts—including Senate Majority Leader Devin LeMahieu. Multiple districts now align with areas carried by Kamala Harris in 2024, and analysts note Democrats can reach a majority by flipping a small number of targeted open or lean seats while holding their own. The closely divided chamber and limited remaining campaign window keep the outcome sensitive to turnout and late developments in four key races.