Staggered Senate
Senators serve four-year terms; half the seats are on the ballot each election.
Iowa › Iowa State Senate · November 3, 2026 · Updated Oct 16, 2026
Iowa State Senate District 21
Projected flip: Republican-held seat, Democrats favored (93%).
Matson is clearly favored to win: Matson wins in about 19 of every 20 simulations.
Matson (D)
93%
chance of winning
Hollinrake (R)
7%
- Average margin
- D+10.9
- 80% of outcomes
- D+2 to D+21
- Partisan lean
- R+2
- Polls
- No pollsmodel only
Projected flip: Republican-held seat, Democrats favored (71%).
Matson is favored to win: Matson wins in about 2 of every 3 simulations.
Matson (D)
71%
chance of winning
Hollinrake (R)
29%
- Average margin
- D+5.1
- 80% of outcomes
- R+8 to D+18
- Partisan lean
- R+2
- 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
Democratic
Heather Matson
Republican
John Hollinrake
What goes into the forecast
Every ingredient's estimate of the final margin.
- National environment
- D+9.5Election Day forecast
- Iowa state offices
- +1.4Polls for governor, statewide and legislative races · details
- Environment here
- D+10.9Used 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) | 0 |
| Fundraising edge (log ratio of individual money) | 0.92 |
| Elected-experience edge | 0.67 |
| First-term incumbent | 0 |
| Seat's last result vs. expectation | 2.3 |
| 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 R+2: 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
- 51,235
- People per km²
- 646
- Adults with a B.A.+
- 50%
- White, no degree
- 44%of adults
- White 86%
- Hispanic 5%
- Black 2%
- Asian 4%
- Other / multiracial 3%
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
40,004 two-party votes · R+2.2 · R+0.7 vs. the nation✓ Donald Trump (R)51.1%
Kamala Harris (D)48.9%
2022
29,256 votes · R+1.9✓ Mike Bousselot (R)50.9%
Todd Brady (D)49.0%
2020 President Vote in this district
36,491 two-party votes · D+0.6 · R+3.9 vs. the nation✓ Joe Biden (D)50.3%
Donald Trump (R)49.7%
2018 Earlier district lines
31,056 votes · D+32.2✓ Claire Celsi (D)66.0%
Brian B Bales (R)33.8%
2016 President Vote in this district
26,786 two-party votes · R+6.3 · R+8.5 vs. the nation✓ Donald Trump (R)53.1%
Hillary Clinton (D)46.9%
2014 Earlier district lines
17,851 votes · Uncontested by the other party✓ Matt McCoy (D)100.0%