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Florida › U.S. House of Representatives · November 3, 2026 · Updated Oct 16, 2026
Florida's 21st District
Mast is clearly favored to win: Mast wins in about 19 of every 20 simulations.
Martin (D)
7%
chance of winning
Mast (R)
93%
- Average margin
- R+10.1
- 80% of outcomes
- R+19 to R+2
- Partisan lean
- R+15
- Polls
- No pollsmodel only
Mast is clearly favored to win: Mast wins in 5 of every 6 simulations.
Martin (D)
17%
chance of winning
Mast (R)
83%
- Average margin
- R+8.5
- 80% of outcomes
- R+20 to D+3
- Partisan lean
- R+15
- 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
James Martin
Lieutenant commander in the U.S. Coast Guard Reserve
- Experience
- No elected office
- Raised
- $772.6K
- From individuals
- $619.2K
- Spent
- $690K
- Cash on hand
- $82.6K
Money: FEC, through Sep 30, 2026.
RepublicanIncumbent
Brian Mast
Incumbent U.S. representative
- Experience
- Statewide office or Congress
- Raised
- $4.9M
- From individuals
- $3.7M
- Spent
- $3.8M
- Cash on hand
- $2.9M
Money: FEC, through Sep 30, 2026.
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
- Southeast adjustment
- −1.9How 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) | -1.38 |
| Elected-experience edge | -1 |
| 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.
The district
Lean R+15: 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
- 815,792
- People per km²
- 169
- Adults with a B.A.+
- 36%
- White, no degree
- 39%of adults
- White 60%
- Hispanic 19%
- Black 14%
- Asian 2%
- 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 Earlier district lines
449,401 votes · R+23.6✓ Brian J. Mast (R)61.7%
Thomas Witkop (D)38.1%
2024 President Vote in this district
446,763 two-party votes · R+16.4 · R+14.9 vs. the nation✓ Donald Trump (R)58.2%
Kamala Harris (D)41.8%
2022 Earlier district lines
328,505 votes · R+27.0✓ Brian J Mast (R)63.5%
Corinna Balderramos Robinson (D)36.5%
2020 Earlier district lines
403,365 votes · D+20.3✓ Lois Frankel (D)59.0%
Laura Loomer (R)39.1%
Charleston Malkemus (I)1.9%
2020 President Vote in this district
471,276 two-party votes · R+9.9 · R+14.5 vs. the nation✓ Donald Trump (R)55.0%
Joe Biden (D)45.0%
2018 Earlier district lines
1 votes · Uncontested by the other party✓ Lois Frankel (D)100.0%
2016 Earlier district lines
335,861 votes · D+28.2✓ Lois Frankel (D)62.7%
Paul Spain (R)35.1%
W Michael "mike" Trout (I)2.1%
2016 President Vote in this district
369,611 two-party votes · R+9.9 · R+12.1 vs. the nation✓ Donald Trump (R)55.0%
Hillary Clinton (D)45.0%