| Election Name: | 2020 Wisconsin Senate election |
| Country: | Wisconsin |
| Type: | legislative |
| Ongoing: | no |
| Previous Election: | 2018 Wisconsin Senate election |
| Previous Year: | 2018 |
| Next Election: | 2022 Wisconsin Senate election |
| Next Year: | 2022 |
| Seats For Election: | 16 of 33 seats in the Wisconsin State Senate |
| Majority Seats: | 17 |
| Election Date: | November 3, 2020 |
| Image1: | Sen. Fitzgerald (3523124714).jpg |
| Image1 Size: | x150px |
| Leader1: | Scott Fitzgerald (retired) |
| Party1: | Republican Party of Wisconsin |
| Last Election1: | 11 seats, 52.31% |
| Seats Before1: | 18 |
| Seats Needed1: | 6 |
| Seats1: | 10 |
| Seats After1: | 21 |
| Seat Change1: | 2 |
| Swing1: | 1.5 |
| Popular Vote1: | 1,665,487 |
| Percentage1: | 53.8% |
| Image2 Size: | x155px |
| Leader2: | Janet Bewley |
| Party2: | Democratic Party of Wisconsin |
| Last Election2: | 6 seats, 46.90% |
| Seats Before2: | 13 |
| Seats Needed2: | 11 |
| Seats2: | 6 |
| Seats After2: | 12 |
| Seat Change2: | 2 |
| Swing2: | 1.6 |
| Popular Vote2: | 1,402,108 |
| Percentage2: | 45.29% |
| President | |
| Before Party: | Republican Party of Wisconsin |
| Before Election: | Roger Roth |
| After Election: | Chris Kapenga |
| After Party: | Republican Party of Wisconsin |
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 - 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.
| Seats | Party (majority caucus shading) | Total | |||
|---|---|---|---|---|---|
| Democratic | Republican | ||||
| nowrap colspan=2 | Last election (2018) | 6 | 11 | 17 | |
| nowrap style="font-size:80%" colspan=2 | Total after last election (2018) | 14 | 19 | 33 | |
| nowrap style="font-size:80%" colspan=2 | Total before this election | 13 | 18 | 31 | |
| Up for election | 8 | 8 | 16 | ||
| of which: | nowrap style="font-size:80%" | Incumbent retiring | 3 | 2 | 5 |
| nowrap style="font-size:80%" | Vacated | 1 | 1 | 2 | |
| nowrap style="font-size:80%" | Unopposed | 3 | 2 | 5 | |
| nowrap style="background:#ccc" colspan=2 | This election | 6 | 10 | 16 | |
| nowrap style="font-size:80%" colspan=2 | Change from last election | 1 | 1 | ||
| nowrap style="font-size:80%" colspan=2 | Total after this election | 12 | 21 | 33 | |
| nowrap style="font-size:80%" colspan=2 | Change in total | 2 | 2 | ||
Seats where the margin of victory was under 10%:
| District | Incumbent | This race | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Member | Party | First elected | Status | Primary candidates[8] [9] | General election candidates[10] | Result | |||||
| 2 | Robert Cowles | Republican | 1987 | Running | Robert Cowles (Republican) | Robert Cowles (Rep.) | Incumbent re-elected | ||||
| 4 | Lena Taylor | Democratic | 2004 | Running | Lena Taylor (Democratic) | Lena Taylor (Dem.) | Incumbent re-elected | ||||
| 6 | La Tonya Johnson | Democratic | 2016 | Running | Incumbent re-elected | ||||||
| 8 | Alberta Darling | Republican | 1992 | Running | Incumbent re-elected | ||||||
| 10 | Patty Schachtner | Democratic | 2018 | Running | Incumbent lost New member elected Republican gain | ||||||
| 12 | Tom Tiffany | Republican | 2012 | Vacant | Incumbent vacated office to run for U.S. Representative New member elected Republican hold | ||||||
| 14 | Luther Olsen | Republican | 2004 | Not running | Incumbent retired New member elected Republican hold | ||||||
| 16 | Mark F. Miller | Democratic | 2004 | Not running | Incumbent retired New member elected Democratic hold | ||||||
| 18 | Dan Feyen | Republican | 2016 | Running | Incumbent re-elected | ||||||
| 20 | Duey Stroebel | Republican | 2014 | Running | Duey Stroebel (Republican) | Duey Stroebel (Rep.) | Incumbent re-elected | ||||
| 22 | Robert Wirch | Democratic | 1996 | Running | Robert Wirch (Democratic) | Robert Wirch (Dem.) | Incumbent re-elected | ||||
| 24 | Patrick Testin | Republican | 2016 | Running | Incumbent re-elected | ||||||
| 26 | Fred Risser | Democratic | 1962 | Not running | Kelda Roys (Dem.) | Incumbent retired New member elected Democratic hold | |||||
| 28 | Dave Craig | Republican | 2016 | Not running | Incumbent retired New member elected Republican hold | ||||||
| 30 | Dave Hansen | Democratic | 2000 | Not running | Incumbent retired New member elected Republican gain | ||||||
| 32 | Jennifer Shilling | Democratic | 2011 | Vacant | Incumbent vacated office New member elected Democratic hold | ||||||