Stelson's PA-10 Odds Drop 12 Points as First Fall Poll Shows Perry +3

The latest public poll of Pennsylvania's 10th Congressional District shows Republican incumbent Scott Perry leading Democrat Janelle Stelson by 3 points, according to a Franklin & Marshall College survey conducted September 9 through 20. That result sits in tension with independent forecast models that still rate Stelson as the favorite. Prediction markets, which had priced her well above both the polls and the forecasters, corrected hard in her direction of risk over the past three days.

Stelson's implied probability of winning PA-10 fell from 86% to 74%, a 12-percentage-point drop that ranks among the sharpest repricing events of the 2026 House cycle. The move lands her closer to, but still above, the 68% win probability published by Call the Map as of September 26.

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Scott Perry Leads Stelson by 3 Points in Latest PA-10 Poll, but Forecasters Still Favor Democrats

Yes, there is recent public polling for this race. The Franklin & Marshall College survey, released September 24, found Perry at 47% and Stelson at 44% among 378 registered voters in the district. Twenty-two percent of respondents cited the economy and finances as their top concern, a factor that has historically favored incumbents in midterm cycles.

That 3-point Perry lead is narrow enough to fall within a typical survey's margin of error for a sample this size. It does not represent a decisive advantage. But it matters because it is the first high-quality poll of the fall campaign season, and it shows Perry ahead rather than behind.

Call the Map's forecast, which incorporates this poll alongside three earlier surveys and a structural model, still gives Stelson a 68.4% chance of winning with a predicted margin of D+2.6. The model's 80% confidence interval spans from R+4.6 to D+9.8, meaning it sees real paths where Perry wins comfortably. The earlier polls in the aggregate (from Normington Petts, Public Policy Polling) showed Stelson leads of 3 to 6 points, all conducted before mid-2026.

The key tension: a forecast that says D+2.6, a fresh poll that says R+3, and a prediction market that until this week said Stelson was nearly a lock.

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Stelson's Prediction Market Odds Drop 12 Points in Three Days

At 86%, prediction markets had been pricing Stelson as a near-certainty. That figure sat 18 percentage points above Call the Map's 68% probability, an unusually wide gap for a competitive House race with limited polling. The 12-point correction closes roughly two-thirds of that spread.

No confirmed public catalyst explains the timing. The Franklin & Marshall poll was published September 24, which falls within the three-day window, and it represents the first data showing Perry ahead. That alone could account for a correction, particularly if traders had been anchoring to older, more favorable Democratic polls.

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Janelle Stelson (D)

Consensus YES price across 4 venues

82%average

Polymarket USBest YES price80¢Kalshi81¢Polymarket82¢PredictIt88¢

Scott Perry (R)

Consensus YES price across 4 venues

17%average

KalshiBest YES price21¢Polymarket US21¢Polymarket21¢PredictIt36¢

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There is also a platform-level story here. Kalshi prices Stelson at 80%, while PredictIt has her at 67%. That 13-percentage-point gap between platforms suggests fragmented liquidity and potentially different trader populations reaching different conclusions from the same data. Neither platform has converged to the other, which means the market-implied probability sits somewhere in a wide band rather than at a single number.

The honest read: 86% was almost certainly too high given available evidence, and 74% is a correction toward what the data supports. Whether the market overshoots to the downside depends on what comes next.

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The Case Against Stelson: Why 74% Could Still Be Too Generous

Scott Perry is a five-term incumbent with deep name recognition in a district that, despite redistricting, still leans Republican at the presidential level. His advantages are structural and not easily captured by generic ballot polling.

The Franklin & Marshall poll's finding that 22% of voters prioritize the economy is worth taking seriously. In midterm cycles, economic dissatisfaction tends to punish the president's party. If the national environment shifts even modestly toward Republicans between now and November 4, Stelson's narrow modeled edge evaporates. Call the Map's own confidence interval includes outcomes where Perry wins by nearly 5 points.

There is also the fundraising paradox. Stelson raised $1.4 million in Q1 2026, topping all Pennsylvania congressional candidates. High fundraising in a challenger race often signals competitiveness, but it can also reflect national donor enthusiasm that does not translate to local vote margins. Perry's incumbency advantage, including constituent services, franking privileges, and local media presence, is the kind of asset that polls tend to undercount.

A televised debate on October 14, hosted by ABC27, represents the next inflection point. Perry is a combative debater. Stelson, a former local news anchor, has strong on-camera skills. The outcome could move both polls and market prices in either direction.

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What the Price Means Now and What Resolves the Gap

At 74%, the market implies Stelson wins roughly three times out of four. That is a clear favorite status, but not a dominant one. For context, a 74% implied probability is roughly equivalent to the home team's win probability in a closely matched NFL game. It means Perry wins more than one in four times.

The gap between the market (74%) and Call the Map (68%) has narrowed considerably from where it stood three days ago. The rapid correction suggests traders are now pricing this race more in line with the quantitative evidence rather than speculating on a Stelson blowout.

What would push Stelson back toward 86%? A post-debate poll showing her ahead by 5 or more points, a national environment shift toward Democrats, or Perry committing a serious unforced error. What would push her below 68%? Another poll confirming Perry's lead, a tightening national generic ballot, or a debate performance that reinforces voter concerns about Stelson's relative lack of legislative experience.

For live pricing and resolution details, track the full PA-10 House race odds through Election Day on November 4.