Our Ohio Senate estimate moves 18.5 points toward Brown in six days

Our model now gives Democrat Sherrod Brown an 80 in 100 chance of winning the Ohio Senate special election against Republican incumbent Jon Husted. In our run of September 23 at 10:02 AM ET, that figure was 61%. Our model puts the change at 18.5 points of Democratic win probability over six days.

The expected margin moved with it. Our model's mean margin is now D+4.7, up from D+1.6 in the earlier run. The range between our 5th and 95th percentile outcomes runs from R+4.5 to D+13.9, compared with R+7.9 to D+11.2 before. That range still includes a Husted win, and our model gives him a 20% chance.

One poll in our data was fielded entirely after the earlier run. A Marist University survey of 1,298 registered voters, fielded September 24-27, had Brown at 51% and Husted at 43%. It is the largest sample among the Ohio polls available to us.

A Quantus Insights survey of 695 likely voters, fielded September 21-23, closed on the day of the earlier run. In a two-way question it had Brown at 47.6% and Husted at 47.2%. With other and independent options offered, it had Brown at 47.3% and Husted at 46.8%. Both versions show a close race.

The two polls measure different populations, registered voters in the Marist survey and likely voters in the Quantus survey, and they point in different directions on the size of any Brown advantage. Nationally, our model gives Democrats a 57% chance of winning Senate control, with 51 seats needed.