nijinnUS Midterms 2026
Updated Oct 16, 2026, 1:45 PM ET
House · 3 November 2026

FL-21 House 2026

92.2% RBrian Mast leads TruthIndex™Safe R
Polymarket
92.5%
Kalshi
91.9%
Spread
0.6 pts
24h
–
7 days
+2.4
Updated
Oct 16, 2026, 1:45 PM ET
Latest coverage

Live News

Recent coverage for FL-21 House.

  1. Korut Uji Coba Rudal Balistik Baru dari Kapal Selam

    The article reports North Korea test-fired a new ballistic missile from a submarine, signaling an attempt to diversify its submarine-launched launch options.

    katakini.comMartin
  2. ANCA Endorses Congressional Allies; Grades Members of Congress on Pro-Armenian Priorities

    Rep. Scott Eugene DesJarlais (R-TN-04) – C [...] Rep. Janelle Bynum (D-OR-05) – C

    asbarez.comMcBathBeattyHarderMorelleJoyceNeguseHayesSolisConawayReschenthalerBilirakisThompsonCisnerosWhitesidesLatimerPalmerAmoLucasBurlisonValadaoRouzerJoyceStrongWestermanPettersenMastJackBoyleShermanKnottWagnerMejiaAdamsMcDowellBeanCorreaUnderwoodCastorJacksonWilsonHimesJeffriesDavisTranBentzKurdian
  3. Anthropic PAC Splits $257K Evenly Between Parties

    The article reports that the Anthropic PAC split a total of $257,000 evenly between political parties and highlights several House Republicans who received funds, including Rep. Brian Mast (FL-21) of Florida.

    Yahoo NewsMast
  4. What's on my ballot? Voter Guide 2026

    Voters statewide will also decide three constitutional amendments appearing on the Florida ballot.

    WPTVFrankelMoskowitzMartinAdeimyAskarMast
  5. Jesuits rejected candidate for opposing Fr. James Martin's LGBT promotion

    A Jesuit prospect, Peter Swindal, says he was rejected from entering the Jesuits after a 9-hour interview in which he criticized Father James Martin’s LGBTQ advocacy.

    lifesitenews.comMartin
More coverage 2
  1. Palm Beach and Treasure Coast voters face statewide, House and local races

    The article highlights four U.S. House races in the Palm Beach and Treasure Coast area as covered by WPTV, including District 21 where James Martin (D) runs against incumbent Brian Mast (R).

    sunstatenews.comFrankelMartinAdeimyAskarMast
  2. Anthropic's PAC spent over $250K in third-quater, splitting between parties

    The Hill reports that Anthropic’s Political Action Committee (PAC) spent over $250,000 in the third quarter, distributing funds to multiple Republican recipients, including Florida Rep. Brian Mast (FL-21).

    The HillMast

Brian Mast, last 60 days

How to read this chart

The green line is the TruthIndex™, the chance of this outcome. It combines the prices on both venues and gives more weight to the venue with more money in its order book. The two thinner lines are Polymarket's and Kalshi's own prices, and the grey band between them shows how far apart the two venues are.

The pale bands behind the lines are the rating zones (Toss-up, Lean, Likely and Safe), so you can see when the race moved from one rating to another. Move along the chart, or use the arrow keys, to read the values for each day.

More in Methodology
TruthIndex™PolymarketKalshiGap between the venuesRating zones

All outcomes

OutcomeTruthIndex™PolymarketKalshiSpread24h
RBrian Mast 92.2% 92.5% 91.9% 0.6 pts –
DJames Martin 8.1% 8.2% 8.0% 0.1 pts –
PolymarketKalshi

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<p style="margin:4px 0 0;font:12px/1.4 Arial,sans-serif">Live odds: <a href="https://midterms.nijinn.io/house/fl-21/?utm_source=embed&amp;utm_medium=embed-credit&amp;utm_campaign=midterms-2026&amp;utm_content=house-fl-21">Nijinn US Midterms 2026</a></p>

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Candidates & Background

Brian Mast

Brian Mast

Republican U.S. Representative for Florida's 21st congressional district (since 2017)

Brian Mast, a Republican Army veteran who has represented Florida's 21st congressional district since 2017 and chairs the House Foreign Affairs Committee, seeks re-election in 2026 against Democrat James Martin.

Born 1980 · Grand Rapids, Michigan

James Martin

Democratic

James Martin, a lieutenant commander in the U.S. Coast Guard Reserve, is the Democratic nominee for Florida's 21st congressional district in 2026, facing Republican incumbent Brian Mast in the November 3 general election.

Margin of victory

Each venue's margin market, shown on its own: the two venues set their ranges differently.

Kalshi2.4K contracts

Florida's 21st District margin of victory

Mast, 1+ pts
89.3%
Mast, 4+ pts
80.5%
Mast, 7+ pts
66.0%
Mast, 10+ pts
53.5%
Mast, 13+ pts
38.5%
Mast, 16+ pts
25.5%
Mast, 19+ pts
15.0%
Mast, 22+ pts
7.5%
Mast, 25+ pts
7.6%
implied
Source: Kalshi market

Polymarket$11.4K traded

FL-21 House Election Margin of Victory

Democrat Wins
–
Republican 0-5%
6.6%
Republican 5-10%
24.4%
Republican 10-15%
25.5%
Republican 15-20%
20.0%
Republican 20-25%
–
Republican 25-30%
5.5%
Republican 30%+
2.4%
Source: Polymarket market

Each venue's market

Polymarket$27.7K traded

Prices which party wins.

Brian Mast: Counted · bid 92.0% / ask 93.0% · $5.4K within 5 pts

This market will resolve according to the party of the candidate who wins the FL-21 congressional district seat in the U.S. House of Representatives in the 2026 midterm elections. The midterm elections will take place on November 3, 2026. ​A candidate's party will be determined by their ballot-listed or otherwise identifiable affiliation with that party at the time all of the 2026 House elections are conclusively called by this market's resolution sources. A candidate without a ballot-listed affiliation to either the Democrat or Republican parties will be considered a member of one of these parties based on the party with which they most recently expressed their intent to caucus at the time all of the House elections are conclusively called by this market's resolution sources. This market will resolve based on the result of the election as indicated by a consensus of credible reporting. If there is ambiguity, this market will resolve based solely on the official results as reported by the United States government, specifically the Federal Election Commission (https://www.fec.gov/).

Full rules on Polymarket

Kalshi7.1K contracts traded

Prices which party wins.

Brian Mast: Counted · bid 90.7% / ask 93.0% · $4.1K within 5 pts

Contract shown: Brian Mast

If the House member sworn in for FL-21 for the term beginning in 2027 is a member of the Republican Party, then the market resolves to Yes.

This market is eligible for accelerated determination after a consensus of media organizations project the winner. See full rules for details.

Full rules on Kalshi

Also in Florida

  1. Florida Senate (special)R91%
  2. Florida GovernorR79%
  3. FL-01 HouseR96%
  4. FL-02 HouseR92%
  5. FL-03 HouseR95%
  6. FL-04 HouseR86%
  7. FL-05 HouseR93%
  8. FL-06 HouseR97%