Model trims Warner's win probability in Virginia as its range widens

Our model now gives Mark Warner, the Democratic incumbent, a 90 in 100 chance of winning the Virginia Senate race, and Republican Bert Mizusawa a 10% chance. A week ago, in our run of August 24, the same numbers were 99% and 1%. That is a move of 8.8 points of Democratic win probability toward the Republican over seven days.

The central estimate barely moved. Our model's mean margin is D+14.3, against D+14.6 last week. What changed is the spread around it. The 5th-to-95th percentile range in the August 24 run ran from D+3.6 to D+25.5, entirely on the Democratic side. This week it runs from R+4.4 to D+32.7, so the bottom of the range now crosses zero. A distribution that wide leaves room for Republican outcomes that last week's did not, which is most of the difference in the win probability.

No new Virginia survey appears in this payload. The only poll we hold for this race is a Responsive Management survey for Virginia Commonwealth University of 806 adults, fielded December 18, 2024 to January 15, 2025, with Warner at 45% and an unnamed Republican at 38%; the payload gives no margin of error for it. That poll predates both of the runs being compared here and cannot account for the change between them. The model moved; on the evidence in front of us, the cause is not something we can name.

Nationally, our model gives Democrats a 49% chance of Senate control and Republicans 50%, with a mean of 50.2 Democratic seats. Democrats need 51 seats for control and Republicans 50, because the vice president is a Republican and a 50-50 tie goes to their side. Our generic-ballot average stands at D+6.5 across 28 polls over the past 45 days.