Democratic
Julie Fortier
Research microbiologist and Air Force veteran
- Experience
- No elected office
- Raised
- $145.6K
- From individuals
- $136.6K
- Spent
- $103.5K
- Cash on hand
- $42.1K
Money: FEC, through Sep 30, 2026.
Illinois › U.S. House of Representatives · November 3, 2026 · Updated Oct 16, 2026
Illinois's 12th District
Bost is very likely to win: Bost wins in more than 99 of every 100 simulations.
Fortier (D)
<1%
chance of winning
Bost (R)
>99%
- Average margin
- R+36.1
- 80% of outcomes
- R+45 to R+28
- Partisan lean
- R+44
- Polls
- No pollsmodel only
Bost is very likely to win: Bost wins in more than 99 of every 100 simulations.
Fortier (D)
<1%
chance of winning
Bost (R)
>99%
- Average margin
- R+36.9
- 80% of outcomes
- R+49 to R+26
- Partisan lean
- R+44
- Polls
- No pollsmodel only
Range of outcomes
Final margin across our simulations; the white dashes mark the middle 80%.
The candidates
What goes into the forecast
Every ingredient's estimate of the final margin.
- National environment
- D+9.5Election Day forecast; federal races run in it
- Swing reaching this office
- 78%Of a shift in the environment, from past House races since 2016
- Midwest adjustment
- +1.4How House 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) | -1.96 |
| Elected-experience edge | -1 |
| First-term incumbent | 0 |
| Seat's last result vs. expectation | -1.89 |
| Incumbent's last result vs. expectation | -1.89 |
Polls
No public polls of this race. The forecast relies on fundamentals and on polling of similar places.
The district
Lean R+44: 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
- 744,931
- People per km²
- 20
- Adults with a B.A.+
- 24%
- White, no degree
- 67%of adults
- White 87%
- Hispanic 3%
- Black 5%
- Asian 1%
- Other / multiracial 4%
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
367,629 votes · R+48.4✓ Mike Bost (R)74.2%
Brian Roberts (D)25.8%
2024 President Vote in this district
366,774 two-party votes · R+44.1 · R+42.6 vs. the nation✓ Donald Trump (R)72.0%
Kamala Harris (D)28.0%
2022
291,253 votes · R+50.0✓ Mike Bost (R)75.0%
HOMER âCHIPâ MARKEL (D)25.0%
2020 Earlier district lines
322,416 votes · R+20.9✓ Mike Bost (R)60.4%
Raymond C Lenzi (D)39.6%
2020 President Vote in this district
382,688 two-party votes · R+43.5 · R+48.1 vs. the nation✓ Donald Trump (R)71.8%
Joe Biden (D)28.2%
2018 Earlier district lines
261,543 votes · R+6.4✓ Mike Bost (R)51.6%
Brendan Kelly (D)45.4%
Randy Auxier (G)3.0%
2016 Earlier district lines
313,002 votes · R+15.5✓ Mike Bost (R)54.3%
Charles "c J" Baricevic (D)39.7%
Paula Bradshaw (G)6.0%
2016 President Vote in this district
354,559 two-party votes · R+45.2 · R+47.4 vs. the nation✓ Donald Trump (R)72.6%
Hillary Clinton (D)27.4%