Staggered Senate
Senators serve four-year terms; half the seats are on the ballot each election.
25 of 50 seats on the ballot; 25 holdovers (6 D, 19 R) serve until a later election.
Iowa · 2026 forecast · Updated Oct 16, 2026
Who will control the Iowa State Senate?
25 of 50 seats are on the ballot; the others are elected in alternate years. 26 seats make a majority. 34 make the two-thirds supermajority that can override a veto.
Republicans are very likely to control the Iowa State Senate (>99%).
Democrats
<1%
chance of control
Republicans
>99%
- Avg. D seats
- 18.480% range 16–21
- Avg. R seats
- 31.680% range 29–34
- Now
- 17 D · 32 R · 1 vacant25 up this year
Chance Republicans win a two-thirds supermajority (34+ seats): 10%
17 D nowMarks: two-thirds supermajority for each party32 R now
Republicans are very likely to control the Iowa State Senate (>99%).
Democrats
<1%
chance of control
Republicans
>99%
- Avg. D seats
- 17.380% range 15–19
- Avg. R seats
- 32.780% range 31–35
- Now
- 17 D · 32 R · 1 vacant25 up this year
Chance Republicans win a two-thirds supermajority (34+ seats): 31%
17 D nowMarks: two-thirds supermajority for each party32 R now
- Solid D
- Likely D
- Lean D
- Toss-up
- Lean R
- Likely R
- Solid R
- Holdover, not up this year
Race ratings
All 25 races, grouped by the leader's chance of winning.
2 seats projected to flip: 1 R→D, 1 D→R. 1 more is a toss-up that could change parties (flip risk).
2 seats projected to flip: 1 R→D, 1 D→R. 2 more are toss-ups that could change parties (flip risk).
Columns follow the chance of winning: Toss-up 40–60%, Lean 60–80%, Likely 80–95%, Solid 95%+. The square shows who holds the seat now (■ Democrats, ■ Republicans). flip: projected to change parties, in the color of the party favored to gain it. risk: a toss-up (40–60%) that could change parties. Faded: no major-party opponent.
The map
Each district colored by the leader's chance of winning. Hover for details; click for the race.
Iowa
Des Moines
- Solid D
- Likely D
- Lean D
- Toss-up
- Lean R
- Likely R
- Solid R
- Projected flip (stripes: party holding it now)
Seats to watch
The closest races (Lean or Toss-up, Horizon), and the seats most likely to change parties.
Closest races
Most likely to flip
SD-21Heather MatsonJohn HollinrakeD flipD flip93%to flip71%to flip SD-35Mike ZimmerJoe StuttingR flipR flip67%to flip90%to flip SD-47Nikhil WagleScott WebsterFlip riskFlip risk59%to flip48%to flip SD-41Tom WieckKerry Gruenhagen34%to flip39%to flip SD-23Tony ThompsonWes Enos27%to flip17%to flip SD-1Catelin DreyChristopher ProschFlip risk20%to flip58%to flip SD-29Jim VowelsSandy Salmon1%to flip2%to flip SD-33Mary Ungs-SogaardCarrie Koelker1%to flip3%to flip SD-19Zachary MechamBarb Kniff McCulla<1%to flip1%to flip SD-37Molly DonahueRandy Marzen<1%to flip3%to flip
How this chamber is elected
Rules that shape these races and the forecast.
How the odds have moved
Chance of winning control, by forecast date.
Updated nightly. Each day is the current model run on the polls that had ended by then (how).
Updated nightly. Each day is the current model run on the polls that had ended by then (how).
Every outcome we simulated
Democratic seats across 40,000 simulations. Darker bars: the middle 80%.
Every race
25 races, 7 without a contest between the major parties.
25 races
| District | Candidates | Chance of winning (D · R) | Avg. margin | Rating | Lean | Polls |
|---|---|---|---|---|---|---|
| SD-1Flip risk | ● Catelin DreyINC● Christopher Prosch | D+6.5R+1.9 | R+9 | — | ||
| SD-3 | ● Mike Frantz● Lynn EvansINC | R+34.7R+38.7 | R+47 | — | ||
| SD-5 | ● No Democrat● Dave RowleyINCAlso: Rachel Gravert (I) | No Democrat on the ballotNo Democrat on the ballot | — | R+40 | — | |
| SD-7 | ● No Democrat● Kevin AlonsINC | Republican unopposedRepublican unopposed | — | R+41 | — | |
| SD-9 | ● James Uhlenkamp● Steve Baier | R+30.6R+35.3 | R+43 | — | ||
| SD-11 | ● Sinikka Waugh● Hollie Zajicek | R+8.6R+14.1 | R+21 | — | ||
| SD-13 | ● Brenda Case● Jeff Kulmatycki | R+24.4R+32.8 | R+39 | — | ||
| SD-15 | ● Tony BisignanoINC● No Republican | Democrat unopposedDemocrat unopposed | — | D+19 | — | |
| SD-17 | ● Samy El-Baroudi● Ronald Langston | D+46.5D+44.6 | D+39 | — | ||
| SD-19 | ● Zachary Mecham● Barb Kniff McCulla | R+23.6R+26.7 | R+35 | — | ||
| SD-21D flipD flip | ● Heather Matson● John Hollinrake | D+10.9D+5.1 | R+2 | — | ||
| SD-23 | ● Tony Thompson● Wes Enos | R+4.3R+9.1 | R+16 | — | ||
| SD-25 | ● Herman QuirmbachINC● Paul Wacker | D+42.5D+36.4 | D+30 | — | ||
| SD-27 | ● No Democrat● Annette SweeneyINC | Republican unopposedRepublican unopposed | — | R+28 | — | |
| SD-29 | ● Jim Vowels● Sandy SalmonINC | R+18.8R+21.5 | R+29 | — | ||
| SD-31 | ● Timi Brown-Powers● No Republican | Democrat unopposedDemocrat unopposed | — | D+15 | — | |
| SD-33 | ● Mary Ungs-Sogaard● Carrie KoelkerINC | R+18.8R+20.2 | R+28 | — | ||
| SD-35R flipR flip | ● Mike ZimmerINC● Joe Stutting | R+3.3R+12.2 | R+20 | — | ||
| SD-37 | ● Molly DonahueINC● Randy Marzen | D+22.5D+18.7 | D+12 | — | ||
| SD-39 | ● Liz BennettINC● Edward Bernie Hayes | D+33.7D+31.3 | D+25 | — | ||
| SD-41 | ● Tom Wieck● Kerry GruenhagenINC | R+2.8R+2.6 | R+10 | — | ||
| SD-43 | ● Meghann Foster● No Republican | Democrat unopposedDemocrat unopposed | — | D+40 | — | |
| SD-45 | ● Janice WeinerINC● No Republican | Democrat unopposedDemocrat unopposed | — | D+56 | — | |
| SD-47Flip riskFlip risk | ● Nikhil Wagle● Scott WebsterINC | D+1.6R+0.6 | R+7 | — | ||
| SD-49 | ● Cindy WincklerINC● Cynthia Mensendick | D+27.4D+18.0 | D+11 | — |
Lean: how much more Democratic (D+) or Republican (R+) the place voted for president than the nation (2024 weighted 75%, 2020 25%). Ratings follow the chance of winning: Toss-up 40–60%, Lean 60–80%, Likely 80–95%, Solid 95%+. INC = incumbent running. D flip / R flip: another party is favored (60% or more) over the party holding the seat now (hover for the chance it changes parties); Flip risk: the seat is a toss-up (40–60%).