Staggered Senate
Senators serve four-year terms; the odd-numbered districts are on the ballot in midterm years and the even-numbered ones in presidential years.
Wisconsin › Wisconsin State Senate · November 3, 2026 · Updated Oct 16, 2026
Wisconsin State Senate District 15
Spreitzer is very likely to win: Spreitzer wins in 49 of every 50 simulations.
Spreitzer (D)
99%
chance of winning
Fleming (R)
1%
- Average margin
- D+19.0
- 80% of outcomes
- D+10 to D+29
- Partisan lean
- D+9
- Polls
- No pollsmodel only
Spreitzer is clearly favored to win: Spreitzer wins in about 9 of every 10 simulations.
Spreitzer (D)
92%
chance of winning
Fleming (R)
8%
- Average margin
- D+13.5
- 80% of outcomes
- D+1 to D+26
- Partisan lean
- D+9
- Polls
- No pollsmodel only
How this race is decided
Range of outcomes
Final margin across our simulations; the white dashes mark the middle 80%.
The candidates
DemocraticIncumbent
Mark Spreitzer
- Experience
- State legislature
Republican
Scott Fleming
Independent
Christopher Dean
What goes into the forecast
Every ingredient's estimate of the final margin.
- National environment
- D+9.5Election Day forecast
- Wisconsin state offices
- −0.7Polls for governor, statewide and legislative races · details
- Environment here
- D+8.8Used by the fundamentals
- Swing reaching this office
- 58%Of a shift in the environment, from past legislative races since 2016
- Midwest adjustment
- +0.3How legislative races in the region have run against lean and environment lately
Each estimate is a margin before national and statewide uncertainty is simulated. Horizon blends polls, fundamentals and a little of the similar-places estimate, weighting each by how precise it is; Pulse uses polls and similar places only.
Fundamentals inputs
| Incumbency (+1 D, −1 R) | 1 |
| Fundraising edge (log ratio of individual money) | 1.5 |
| Elected-experience edge | 0.67 |
| First-term incumbent | 0 |
| Seat's last result vs. expectation | 0 |
| Incumbent's last result vs. expectation | 0 |
Polls
No public polls of this race. The forecast relies on fundamentals and on polling of similar places in the state.
The district
Lean D+9: how much more Democratic or Republican than the nation it votes for president.
Presidential vote
Precinct results re-aggregated to the current district lines.
Who lives here
- Population
- 175,193
- People per km²
- 90
- Adults with a B.A.+
- 26%
- White, no degree
- 61%of adults
- White 80%
- Hispanic 10%
- Black 4%
- Asian 1%
- Other / multiracial 5%
American Community Survey 2020–2024, aggregated from census tracts.
Past results
Results in the same-numbered district; earlier elections may have used different lines.
2024 President Vote in this district
92,805 two-party votes · D+7.8 · D+9.3 vs. the nation✓ Kamala Harris (D)53.9%
Donald Trump (R)46.1%
2022 Earlier district lines
75,198 votes · D+22.9✓ Mark Spreitzer (D)61.4%
Mark Trofimchuck (R)38.6%
2020 President Vote in this district
89,168 two-party votes · D+12.0 · D+7.4 vs. the nation✓ Joe Biden (D)56.0%
Donald Trump (R)44.0%
2018 Earlier district lines
53,462 votes · Uncontested by the other party✓ Janis Ringhand (D)100.0%
2016 President Vote in this district
77,564 two-party votes · D+11.3 · D+9.1 vs. the nation✓ Hillary Clinton (D)55.7%
Donald Trump (R)44.3%
2014 Earlier district lines
61,149 votes · D+19.0✓ Janis Ringhand (D)59.5%
Brian Fitzgerald (R)40.5%