Our Senate estimate sits near even as the generic ballot average stands at D+8.3

Our model gives Democrats a 58 in 100 chance of winning Senate control, against 42% for Republicans, as of 6:32 a.m. ET on September 30, 34 days before the November 3 election. Democrats need 51 seats for control and Republicans need 50, because the vice president is a Republican and a 50-50 tie goes to the Republicans. Our model's average outcome is 50.9 Democratic seats, just short of the Democratic threshold. In the House, our model puts the Democratic chance of a majority at 99%, with an average of 245.8 Democratic seats against the 218 needed. That House figure is marginally firmer than it should be. Our simulation correlates error nationally, by census division, by state and by district, but it does not correlate demographically similar districts in different places, because we lack the data to do so.

Our generic ballot average stands at D+8.3, drawn from 29 polls over a 45-day window. Recent entries vary widely. A Quinnipiac University survey of 1,032 registered voters, fielded September 24-27, had Democrats at 51% and Republicans at 39%. A YouGov/Economist poll fielded September 25-28 found Democrats ahead 45% to 37% among 1,423 registered voters and 53% to 38% among 1,003 likely voters. Morning Consult's September 21-27 survey of 18,786 likely voters had Democrats at 50.3% and Republicans at 42.8%. A HarrisX/Harris Poll survey for Harvard CAPS, fielded September 26-28, found the race tied at 50% among 2,200 registered voters and close among likely voters, at 51% Democratic to 49% Republican.

Ohio moved the most in our Senate forecast. Our estimate of Sherrod Brown's chance rose to 78% from 61%. A Marist University survey of 1,298 registered voters, fielded September 24-27, had Brown at 51% and Jon Husted at 43%. Maine went the other way, with our Democratic estimate falling to 62% from 75%. In Florida, our Democratic estimate dropped to 20% from 30%. A Change Research poll sponsored by Freedom Project USA, surveying 1,063 likely voters September 25-27, found a close race, with Ashley Moody at 48% and the Democrat at 47%.

Several other races shifted toward Democrats in our model. Minnesota rose to 92% from 83%, Georgia to 94% from 87%, and Kansas to 26% from 19%. In New Hampshire, a Trafalgar Group survey of 1,090 likely voters, fielded September 26-27, had Chris Pappas at 47.4% and the Republican at 40.5%, with 1.1% for other candidates.