2020 Wisconsin Senate election

The 2020 Wisconsin Senate elections were held on Tuesday, November 3, 2020, at the Fall general election in Wisconsin. 16 of the 33 seats in the Wisconsin Senate were up for election&mdash;the even-numbered districts. Before the election, Republicans held 18 seats, Democrats held 13, and two were vacant. Of the seats up for election, seven were held by Republicans, seven were held by Democrats, one was vacated by a Democratic resignation, and one was vacated by a Republican resignation. The primary election was held on August 11, 2020.

Republicans maintained control of the Senate but fell one seat short of a supermajority, defeating one Democratic incumbent and winning an open seat previously held by a Democrat. After the elections, Republicans were set to enter the 105th Wisconsin Legislature with 21 of 33 seats, but one member resigned due to election to another office, leaving them with 20 seats at the start of the legislative term.

Close races
Seats where the margin of victory was under 10%:
 * 1) State Senate district 32, 0.6%
 * 2) State Senate district 8, 8.54%
 * 3) State Senate district 30, 9.4% (gain)

Retiring

 * Dave Craig (R–Vernon), representing District 28 since 2016, announced that he would not seek reelection to a second term in order to get "a break from public life."
 * Dave Hansen (D–Green Bay), representing District 30 since 2000, announced in January 2020 that he would be retiring to spend more time with his family.
 * Mark F. Miller (D–Monona), representing District 16 since 2004, announced in January 2020 that he would not be running for reelection.
 * Luther Olsen (R–Ripon), representing District 14 since 2004, announced in February 2020 that he would not seek reelection, stating, "there comes a time in life when it’s time to move on."
 * Fred Risser (D–Madison), representing District 26 since 1962, announced in March 2020 that he would be stepping down from the Legislature. Upon his retirement, Risser was the longest-serving lawmaker in American history, having served in the Wisconsin State Assembly and Senate for 64 years.

Vacated office before term end

 * Jennifer Shilling (D–La Crosse), who had represented District 32 since 2011 and served as Minority Leader since 2015, resigned her seat on May 15, 2020 in order to explore "unspecified career opportunities."
 * Tom Tiffany (R–Hazelhurst), who had represented District 12 since 2014, left office on May 18, 2020, after winning the special election for Wisconsin's 7th congressional district.