| Election Name: | 2018 Wisconsin Senate election |
| Country: | Wisconsin |
| Type: | legislative |
| Ongoing: | no |
| Previous Election: | 2016 Wisconsin Senate election |
| Previous Year: | 2016 |
| Next Election: | 2020 Wisconsin Senate election |
| Next Year: | 2020 |
| Seats For Election: | 17 of the 33 seats in the Wisconsin State Senate 17 seats needed for a majority |
| 1Blank: | Seats up |
| Image2 Size: | x155px |
| Leader2: | Jennifer Shilling |
| Party2: | Democratic Party of Wisconsin |
| Last Election2: | 7 seats, 50.3% |
| Seats Before2: | 15 |
| Seats Needed2: | 9 |
| Seats2: | 6 |
| Seats After2: | 14 |
| Seat Change2: | 1 |
| Popular Vote2: | 605,142 |
| Percentage2: | 46.9% |
| 1Data2: | 7 |
| Image1: | Sen. Fitzgerald (3523124714).jpg |
| Image1 Size: | x150px |
| Leader1: | Scott Fitzgerald |
| Party1: | Republican Party of Wisconsin |
| Last Election1: | 9 seats, 48.6% |
| Seats Before1: | 18 |
| Seats Needed1: | 9 |
| Seats1: | 11 |
| Seats After1: | 19 |
| Seat Change1: | 1 |
| Popular Vote1: | 675,016 |
| Percentage1: | 52.3% |
| 1Data1: | 10 |
| President | |
| Before Election: | Roger Roth |
| Before Party: | Republican Party of Wisconsin |
| After Election: | Roger Roth |
| After Party: | Republican Party of Wisconsin |
The 2018 Wisconsin Senate elections were held on Tuesday, November 6, 2018, at the Fall general election in Wisconsin. Seventeen of the 33 seats in the Wisconsin Senate were up for election - the odd-numbered districts. Before the election, Republicans held 18 seats and Democrats held 15 seats. Of the seats up for election, 10 were held by Republicans and 7 were held by Democrats. The primary election was held on August 14, 2018.
Republicans maintained control of the Senate, flipping one Democratic-held seat to enter the 104th Wisconsin Legislature with 19 of 33 Senate seats.[1]
Statewide results of the 2018 Wisconsin State Senate election:[2]
| Seats | Party (majority caucus shading) | Total | |||
|---|---|---|---|---|---|
| Democratic | Republican | ||||
| nowrap colspan=2 | Last election (2016) | 7 | 9 | 16 | |
| nowrap style="font-size:80%" colspan=2 | Total after last election (2016) | 13 | 20 | 33 | |
| nowrap style="font-size:80%" colspan=2 | Total before this election | 15 | 18 | 33 | |
| Up for election | 7 | 10 | 17 | ||
| of which: | nowrap style="font-size:80%" | Incumbent retiring | 1 | 0 | 1 |
| nowrap style="font-size:80%" | Vacated | 0 | 0 | 0 | |
| nowrap style="font-size:80%" | Unopposed | 1 | 1 | 2 | |
| nowrap style="background:#ccc" colspan=2 | This election | 6 | 11 | 17 | |
| nowrap style="font-size:80%" colspan=2 | Change from last election | 1 | 1 | ||
| nowrap style="font-size:80%" colspan=2 | Total after this election | 14 | 19 | 33 | |
| nowrap style="font-size:80%" colspan=2 | Change in total | 1 | 1 | ||
| Party | Candi- dates | Votes | Seats | |||||
|---|---|---|---|---|---|---|---|---|
| % | +/– ! | % | ||||||
| 15 | 675,016 | 52.31% | 11 | 1 | 64.71% | |||
| 15 | 605,142 | 46.90% | 6 | 1 | 35.29% | |||
| 1 | 1,776 | 0.14% | 0 | 0.00% | ||||
| 2 | 57 | 0.00% | 0 | 0.00% | ||||
| Scattering | 8,346 | 0.65% | 0 | 0.00% | ||||
| Total | 33 | 1,290,337 | 100.00% | 17 | 100.00% | |||
Seats where the margin of victory was under 10%:
Two special elections were held during 2018 for vacancies in the state Senate. Democrats won both special elections, for a net gain of two seats.
| Dist. | Previous Incumbent | This Election | ||||||
|---|---|---|---|---|---|---|---|---|
| Senator | Party | First elected | Candidate(s) | Result | ||||
| 01 | Frank Lasee | Rep. | 2010 | Incumbent resigned on . New member elected . Democratic gain.[3] | ||||
| 10 | Sheila Harsdorf | Rep. | 2000 | Incumbent resigned on . New member elected . Democratic gain.[4] | ||||
Results of the 2018 Wisconsin State Senate election by district:[2]
| scope=col rowspan=3 | District | scope=col colspan=2 | Democratic | scope=col colspan=2 | Republican | scope=col colspan=2 | Others | Total | scope=col rowspan=3 | Result | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| scope=col colspan=2 style="background:" | ! | scope=col colspan=2 style="background:" | ! | scope=col colspan=2 | ! | ||||||||
| scope=col data-sort-type="number" | Votes ! | scope=col data-sort-type="number" | % ! | scope=col data-sort-type="number" | Votes ! | scope=col data-sort-type="number" | % ! | scope=col data-sort-type="number" | Votes ! | scope=col data-sort-type="number" | % ! | scope=col data-sort-type="number" | Votes |
| 39,414 | 45.42% | 47,289 | 54.50% | 65 | 0.07% | 86,768 | Republican Gain | ||||||
| 36,875 | 97.40% | - | - | 985 | 2.60% | 37,860 | Democratic Hold | ||||||
| 45,591 | 48.75% | 47,836 | 51.15% | 102 | 0.11% | 93,529 | Republican Hold | ||||||
| 56,198 | 66.25% | 28,459 | 33.55% | 165 | 0.19% | 84,822 | Democratic Hold | ||||||
| 31,684 | 41.47% | 44,680 | 58.47% | 45 | 0.06% | 76,409 | Republican Hold | ||||||
| - | - | 59,512 | 95.89% | 2,554 | 4.11% | 62,066 | Republican Hold | ||||||
| 34,385 | 40.90% | 49,668 | 59.07% | 24 | 0.03% | 84,077 | Republican Hold | ||||||
| 54,381 | 96.53% | - | - | 1,952 | 3.47% | 56,333 | Democratic Hold | ||||||
| 31,757 | 45.86% | 37,465 | 54.10% | 26 | 0.04% | 69,248 | Republican Hold | ||||||
| 38,179 | 46.73% | 43,493 | 53.23% | 29 | 0.04% | 81,701 | Republican Hold | ||||||
| 35,111 | 41.91% | 48,603 | 58.01% | 69 | 0.08% | 83,783 | Republican Hold | ||||||
| 29,637 | 40.82% | 42,958 | 59.17% | 11 | 0.02% | 72,606 | Republican Hold | ||||||
| 39,624 | 51.06% | 37,960 | 48.92% | 20 | 0.03% | 77,604 | Democratic Hold | ||||||
| 64,606 | 66.16% | 32,993 | 33.79% | 54 | 0.06% | 97,653 | Democratic Hold | ||||||
| 27,627 | 35.73% | 49,657 | 64.22% | 41 | 0.05% | 77,325 | Republican Hold | ||||||
| 40,073 | 51.67% | 35,684 | 46.01% | 1,804 | 2.33% | 77,561 | Democratic Hold | ||||||
| - | - | 68,759 | 96.85% | 2,233 | 3.15% | 70,992 | Republican Hold | ||||||
| Total | 605,142 | 46.90% | 675,016 | 52.31% | 10,179 | 0.79% | 1,290,337 |