Wisconsin State Senate

The Wisconsin Senate is the upper house of the Wisconsin State Legislature. Together with the Wisconsin State Assembly they constitute the legislative branch of the state of Wisconsin. The powers of the Wisconsin Senate are modeled after those of the U.S. Senate. The Wisconsin Senate is controlled by the Republican Party, as it has been for 20 of the past 22 years (with only the biennium of 2009-2010 as the exception).

The Wisconsin Constitution ties the size of the State Senate to that of the Assembly, by limiting its size to no less than 1/4, nor more than 1/3, of the size of the Assembly. Currently, Wisconsin is divided into 33 Senate Districts (1/3 of the current Assembly membership of 99) apportioned throughout the state based on population as determined by the decennial census, for a total of 33 senators. A Senate district is formed by combining three Assembly districts. Similar to the U.S. Senate, in addition to its duty of reviewing and voting on all legislation passed through the legislature, the State Senate has the exclusive responsibility of confirming certain gubernatorial appointments, particularly cabinet secretaries and members of boards and commissions. Senators are elected for four-year terms, staggered so that approximately half of the Senate is up for election every two years. If a vacancy occurs in a Senate seat between elections, it may be filled only by a special election. The Senate chamber is in the south wing of the Wisconsin State Capitol, in Madison. In February 2024, the legislative maps of the Senate, along with the State Assembly, were redrawn following a court decision that found them to be unconstitutionally gerrymandered in favor of Republicans.