On Our Minds

Latest edition · September 18, 2026

On Our Minds Midterms A Blue House, a Coin Flip Senate

Societe Generale launches its weekly US midterm election forecasting model, projecting an 88% likelihood of a Democratic House takeover and a 54% likelihood of Republicans retaining the Senate. The race for unified Democratic control versus divided government remains a coin flip (44% vs 43.3%), hinged on nine competitive Senate contests.

Heading into the November 3, 2026 US midterm elections, Societe Generale introduces a multi-input quantitative model that blends polling data, Cook Political Report ratings, and prediction markets (Kalshi and Polymarket) while adjusting for historical polling misses. The model indicates that while Democrats are highly favored to retake the House (88%), Senate control remains exceptionally tight, with a 54% probability of Republican retention. Overall, the likelihood of a full Democratic sweep (44%) is virtually tied with a divided Congress (43.3%). Crucial voter issues influencing close contests in states like Alaska and Texas include affordability, energy volatility from Iran tensions, trade tariffs, and local electricity impacts from AI data center expansions.

Key takeaways from the latest edition

• 1.The SG election model projects an 88% probability of Democratic control of the House and a 54% probability of Republican control of the Senate.
• 2.Overall balance of power probabilities show a virtual coin toss between a Democratic sweep (44%) and a divided Congress with a Democratic House and Republican Senate (43.3%).
• 3.While prediction markets favor Democrats flipping key Senate seats to take the chamber, the SG model remains more cautious in states like Texas and Alaska due to historical polling errors and structural lean.

What this series covers

• 2026 U.S Midterms
• Summarizing the Race Landscape: A Close Battle
• What Matters to Voters?
• Assessment
• Appendix: SG Election Model Methodology

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