Democrats hold a strong edge in trader consensus for control of the Wisconsin State Senate following the November 2026 election, reflecting new legislative maps from the Clarke v. Wisconsin Elections Commission ruling and multiple Republican retirements in competitive districts. With 17 odd-numbered seats up and Democrats needing a net gain of two to flip the chamber from the current 18-15 Republican majority, forecasts from Marquette Law School and State Navigate rate the outlook as lean or likely Democratic. Key battlegrounds include open seats in the 5th and 21st districts plus the 17th, where Democratic challengers lead or compete closely based on recent polling and internal surveys. Republicans face headwinds in turnout and candidate recruitment amid these structural shifts, though a handful of toss-up races could still influence the final outcome.