Montana's 1st District margin of victory
Short Answer
The model assigns a meaningfully lower probability than the market for Democrats winning by 3+ points (21.2% model vs 35.0% market). This divergence is likely driven by the district's structural Republican lean, despite expectations for an open seat and an unfavorable national environment to reduce the Republican margin of victory.
1. Executive Verdict
- MT-01 shows a structural Republican lean with R+5 PVI.
- Ryan Busse (D) outpaced Aaron Flint (R) in total fundraising.
- An open seat race is expected to reduce the Republican margin.
- Unfavorable national trends likely reduce the Republican margin.
- No reliable district-level polling is available for 2026.
- Ryan Zinke (R) won MT-01 in 2024 by 7.7 percentage points.
Who Wins and Why
| Outcome | Market | Model | Why |
|---|---|---|---|
| Democrats, 9+ pts | 11.0% | 6.4% | A projected unfavorable national environment is expected to reduce the Republican margin of victory. |
| Democrats, 3+ pts | 35.0% | 21.2% | The shift to an open seat is expected to reduce the Republican margin of victory. |
| Democrats, 6+ pts | 26.0% | 15.4% | Low presidential approval is expected to reduce the Republican margin of victory. |
Current Context
Montana's 1st Congressional District will be an open seat in 2026. In the 2024 election, Republican Ryan Zinke defeated Democrat Monica Tranel in Montana's 1st District by an 8.7-point margin, securing 52.3% of the vote (168,529 votes) compared to Tranel's 44.6% (143,783 votes) [^][^]. However, a significant structural change for 2026 occurred when incumbent Ryan Zinke announced on March 2, 2026, that he would not seek re-election, creating an open-seat race for the district [^][^]. The key dates for the 2026 election include a filing deadline of March 4, 2026, a primary election on June 2, 2026, and the general election on November 3, 2026 [^][^][^].
Prediction markets currently lean Republican for the general election. Current prediction market sentiment suggests Republicans are favored to win the general election in Montana's 1st District, with one platform indicating an implied probability of 57% for Republicans versus 42% for Democrats [^]. A specific prediction market also exists for the "margin of victory" in MT-01, detailing scenarios such as "Republicans win... by 3+ pts" [^]. For the primary races, early signals from prediction markets show Aaron Flint leading the Republican primary with approximately 58% implied probability, while Ryan Busse holds a similar 58% lead in the Democratic primary [^][^].
2. Market Behavior & Price Dynamics
Historical Price (Probability)
Outcome probability
Date
This market began with a very low probability, starting at just 1.0%, suggesting traders initially expected a large margin of victory, likely for the Republican incumbent. However, the price experienced a dramatic and rapid spike to a high of 37.0%. This sharp repricing appears to be a direct reaction to the news that incumbent Ryan Zinke announced he would not seek re-election. This development fundamentally changed the race from one with a known incumbent, who had previously won by a significant margin, to an open-seat contest. The creation of an open seat introduces considerable uncertainty and likely led traders to believe a closer election is much more probable, causing the massive upward adjustment in the contract's price.
Following the peak at 37.0%, the price has seen a minor pullback to its current level of 35.0%, indicating some stabilization after the initial volatile reaction. This suggests that 37.0% is acting as an early resistance level, while the market attempts to find a new consensus price. The overall trading volume of 563 contracts suggests a moderate level of interest in the market. The price shift from near zero to the mid-30s reflects a significant change in market sentiment, moving from a high degree of confidence in a wide margin to a belief that a closer outcome is now a distinct possibility.
3. Market Data
Contract Snapshot
The market resolves to "Yes" if the Democratic Party wins the 2026 U.S. House of Representatives election in Montana's 1st District by 3 percentage points or more; otherwise, it resolves to "No". The margin of victory is precisely calculated as the Democratic Party's vote percentage minus the closest opponent's, with no rounding applied, and verified by official election authorities. The market closes after the outcome occurs, potentially early if certified results are published, but no later than November 3, 2027, with payouts projected 30 minutes after closing.
Available Contracts
Market options and current pricing
| Outcome bucket | Yes (price) | No (price) | Last trade probability |
|---|---|---|---|
| Democrats, 3+ pts | $0.36 | $0.65 | 35% |
| Democrats, 6+ pts | $0.26 | $0.75 | 26% |
| Democrats, 9+ pts | $0.11 | $0.90 | 11% |
Market Discussion
For the 2024 general election in Montana's 1st Congressional District, Zinke received 52.29% of the vote against Tranel's 44.62%, which implied a margin of approximately 7.67 points [^][^]. Prediction markets are actively tracking this race, with a dedicated "margin of victory" market available [^][^]. Separately, another market shows the Republican Party favored to win at 57% versus the Democratic Party at 42%, though this focuses on the winner rather than the specific margin [^].
4. How do the fundraising totals for likely nominees Aaron Flint (R) and Ryan Busse (D) compare ahead of the general election?
| Ryan Busse Fundraising Total | $530,043.18 [^][^][^][^] |
|---|---|
| Aaron Flint Fundraising Total | $453,653 [^][^][^] |
| Ryan Busse Cash on Hand | $368,145.39 (as of March 31, 2026) [^][^][^][^] |
5. What do partisan lean indices and 2025-2026 voter registration data suggest for a Republican margin in an open-seat MT-01 race?
| Cook PVI (MT-01) | R+5 [^] |
|---|---|
| Cook Political Report Rating | Likely Republican [^][^] |
| Polymarket Republican Odds | 57% [^] |
Initial expectations for the MT-01 open-seat race indicate a Republican advantage. The district's Cook Partisan Voting Index (PVI) is R+5, signifying it is approximately five points more Republican than the national average [^]. This assessment is echoed by the Cook Political Report, which categorizes the seat as 'Likely Republican,' suggesting a clear Republican edge rather than a competitive toss-up scenario [^][^]. Further corroboration comes from Polymarket predictions, where traders price Republicans at 57% compared to Democrats at 42% for the 'MT-01 House Election Winner,' indicating a modest Republican lead that is more than a coin-flip but does not project a heavily favored candidate [^].
Montana's voter registration policies limit direct vote margin predictions from registration data. Directly inferring a vote-margin from 2025–2026 voter registration data for MT-01 is challenging because the state does not require voters to register by party [^]. Consequently, any party registration data available typically represents inferred or estimated partisan shares of the electorate rather than official party affiliations [^][^]. This characteristic restricts the ability to directly predict an MT-01 vote outcome from such data alone, as it would necessitate additional modeling for turnout and candidate-specific factors [^][^].
6. How might national political trends, such as presidential approval from June to November 2026, impact the final margin in Montana's 1st District?
| Trump Approval (April 2026) | 43% approve (net -12) [^] |
|---|---|
| Historical House Seat Losses | Average 27 seats (when presidential approval is near 43%) [^] |
| MT-01 Cook Partisan Voter Index | R+5 (heading into 2026) [^] |
Presidential approval significantly influences Montana's 1st District election outcomes [^] . Declining approval for Donald Trump between June and November 2026 is projected to impact the final margin in Montana's 1st District (MT-01) [^]. Broader midterm political analysis suggests that a continued fall in Trump's approval through the autumn could lead to reduced Republican vote margins, including in MT-01's final result [^].
Weak presidential approval historically predicts substantial House seat losses [^] . Tracking in April 2026 reported Trump’s approval around 43% with a net -12, indicating weak approval that could benefit Democrats in the midterms [^]. Historically, presidential approval ratings at approximately 43% on Election Day have typically corresponded to significant House seat losses for the president’s party, averaging about 27 seats [^].
Montana's 1st District's partisan lean amplifies national shifts [^] . MT-01 has a modest Republican lean, as reflected by a Cook Partisan Voter Index of R+5 for 2026 [^]. This partisan tilt suggests that national shifts driven by presidential approval could meaningfully change the final district margin. Market expectations for MT-01's margin of victory are anticipated to adjust based on changes in the national House environment related to presidential approval [^].
7. Is there any reliable, public district-level polling for the MT-01 general election matchup available for the 2026 cycle?
| Ryan Zinke Retirement Date | March 2, 2026 [^][^] |
|---|---|
| Primary Election Date | June 2, 2026 [^][^][^] |
| General Election Date | November 3, 2026 [^][^][^] |
No reliable district-level polling is available for MT-01's 2026 general election. Currently, there is no reliable, publicly available district-level polling specifically for the Montana's 1st Congressional District general election matchup for the 2026 cycle. While a past fact mentioned a poll, its relevance to the general election significantly decreased when Representative Ryan Zinke announced his retirement on March 2, 2026, making the seat open. The research did not provide any specifics about this particular poll, including its results or public availability [^][^].
Election dates and potential matchups remain undetermined for the 2026 cycle. The final general election matchups for MT-01 are not yet established. Both the Democratic and Republican primaries for this district are scheduled for June 2, 2026, with the general election set for November 3, 2026 [^][^][^]. As of May 5, 2026, prediction market probabilities were available concerning a Republican win by specific margins; however, these represent market assessments rather than traditional polling data [^].
8. How did the final margins in comparable R-leaning, open-seat House races in 2022 and 2024 perform relative to their partisan lean?
| Data for R-leaning open seats (2022/2024) | Not available in provided information [^] |
|---|---|
| 2022 House margin comparison (Ballotpedia) | Available, but not restricted to open-seat R-leaning races [^] |
| 2024 Average House margin of victory | 27.3 percentage points (overall) [^] |
Specific data determining final margins in comparable R-leaning, open-seat House races for 2022 and 2024, relative to their partisan lean, is not available. The provided research output lacks the necessary filtered subsets to fully address how these particular races performed. While available resources discuss methodologies for measuring performance, the granular details for 'comparable R-leaning open seats' were not present in the snippets.
For 2022, available data does not specify open-seat races. Ballotpedia offers a comparison between 2020 presidential margins and 2022 U.S. House margins across all districts, which could serve as a general method for assessing performance relative to partisan lean [^]. However, this information is not restricted to open-seat races and does not specifically summarize the subset of 'comparable R-leaning open seats' required for this analysis [^].
Similarly, 2024 data lacks specific subset comparison for R-leaning open seats. Ballotpedia's congressional margin-of-victory analysis provides overall averages, such as an average U.S. House margin of victory of 27.3 percentage points in 2024 [^]. While a 2024 U.S. House results page lists 2020 Presidential margins, 2022 U.S. House margins, and open-seat status for many districts, computing the final margins for the precise criteria of 'comparable R-leaning, open-seat races' would necessitate further filtering and comprehensive table extraction not provided in the snippets [^]. Furthermore, market pages for specific districts, such as Montana's 1st District on Kalshi, do not contain the necessary 2022/2024 historical comparative performance data [^][^].
9. What Could Change the Odds
Key Catalysts
In the 2024 Montana-01 general election, Ryan Zinke (R) won with 52.3% of the vote compared to Monica Tranel (D) at 44.6%, resulting in a 7.7 percentage point margin of victory [^] [^] [^] . House - District 1 Election Results | USA TODAY">[^][^][^]. For the 2026 U.S. House election, a market is available that resolves based on whether the Republican Party secures a victory by at least 3 percentage points [^][^].
Current Polymarket odds for the MT-01 House election winner indicate a 57% probability for the Republican candidate and 42% for the Democratic candidate, with resolution around Nov 4, 2026 [^] . Nevertheless, local reporting preceding the 2026 cycle highlighted a low approval rating for Ryan Zinke, with only 26% approving and 41% being neutral or unfamiliar, suggesting a potential opportunity for Democrats if support is perceived to be softening [^].
Key Dates & Catalysts
- Expiration: November 03, 2027
- Closes: November 03, 2027
10. Decision-Flipping Events
- Trigger: In the 2024 Montana-01 general election, Ryan Zinke (R) won with 52.3% of the vote compared to Monica Tranel (D) at 44.6%, resulting in a 7.7 percentage point margin of victory [^] [^] [^] .
- Trigger: For the 2026 U.S.
- Trigger: House election, a market is available that resolves based on whether the Republican Party secures a victory by at least 3 percentage points [^] [^] .
- Trigger: Current Polymarket odds for the MT-01 House election winner indicate a 57% probability for the Republican candidate and 42% for the Democratic candidate, with resolution around Nov 4, 2026 [^] .
12. Historical Resolutions
No historical resolution data available for this series.
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