Senate near even at 48-52 as our House estimate holds at 93 in 100

Seventy-six days out, our model gives Democrats a 48 percent chance of a Senate majority and Republicans 52 percent. The mean Democratic seat total in our simulations is 50.1, just short of the 51 seats Democrats need; Republicans need 50, because the vice president is a Republican and a 50-50 tie goes to their side. That asymmetry is why a distribution centered close to a split chamber still leans Republican in our numbers.

In the House, our model gives Democrats a 93 in 100 chance of a majority, with a mean of 242.5 seats against the 218 needed for control. One caveat on that figure is ours to make: our simulation draws correlated error at the national, census-division, state and district levels, but it has no term linking demographically similar districts in different places, because we have no cluster data for one. The effect is that our House control probability is marginally firmer than a fuller error model would leave it. We are not putting a number on the gap, and the 93 percent stands as the run's output.

Our generic ballot average is D+6.7, drawn from 25 polls fielded in the last 45 days.

The largest overnight movement in our Senate probabilities came in Alaska, where the Democratic chance rose 9.2 points to 32 percent, and Louisiana, where it fell 8.3 points to 2 percent. Maine moved 4.3 points toward the Democrat, to 79 percent. Ohio moved the other way, down 4.2 points to 63 percent, even as two surveys there showed the Democrat ahead: Wedgewood Polls, fielding August 11-13 among 800 likely voters, had Sherrod Brown at 48 percent and Jon Husted at 44, while Beacon Research/Shaw & Co. Research, fielding August 6-10 among 1,008 registered voters, had Brown at 53 and Husted at 45.

Elsewhere in recent Senate polling, an Emerson College survey of 1,000 likely voters in Texas, fielded August 9-10, put Ken Paxton at 47 percent and James Talarico at 46, a margin too small to separate the two. Idaho produced two very different readings on the same day: Peak Insights, polling 500 likely voters August 11-13, had Jim Risch at 52 percent and independent Todd Achilles at 18, while The Bullfinch Group, polling 608 likely voters on August 13, had Risch at 34 and Achilles at 30. In Massachusetts, UMass Amherst/YouGov surveyed 800 registered voters August 5-12 and found Ed Markey at 51 percent and John Deaton at 30. At the district level, Bedrock Polling surveyed 866 likely voters in Ohio's 7th District August 7-10 and found the Democrat at 43 percent to the Republican's 35.