Ohio Senate moves to even money as Democrats sit at 44 percent in the chamber

Seventy days out, our model gives Democrats a 94 in 100 chance of winning a House majority, against 6 percent for Republicans. The mean outcome in our simulations is 241.1 Democratic seats, with 218 needed for control. One caveat on that figure is ours to make: our House simulation draws error nationally, by census division, by state and by district, but it has no term linking demographically similar districts in different places, because we have no cluster data to build one. The effect is that our House control number is somewhat firmer than a fuller error model would leave it.

The Senate is closer. Our model puts Democratic control at 44 percent and Republican control at 56 percent, with a mean of 49.9 Democratic seats. Democrats need 51 seats for a majority; Republicans need 50, because the vice president is a Republican and a 50-50 tie goes to them.

Our generic ballot average, as of 6:30 a.m. ET, is D+6.5, drawn from 27 polls fielded in the past 45 days. Four of the most recent surveys agree on the margin and differ on the levels. Emerson College, polling 1,000 likely voters August 16-17, had Democrats at 51 percent and Republicans at 43. Echelon Insights, with 1,002 likely voters August 13-17, had it 50-45. The Bullfinch Group, fielding August 14-17, had Democrats up 45-40 among 1,200 adults and 42-37 among 1,000 registered voters. Reuters/Ipsos, also August 14-17, had Democrats ahead 41-36 among 876 registered voters and 35-30 among 1,166 adults.

The largest move on the Senate board was Ohio, where our estimate of the Democratic chance fell 15.1 points to an even 50 percent. Michigan went the other way, up 15.0 points to 58 percent, and Maine rose 10.8 points to 89 percent. Alaska continued to move away from the Democrat, down 9.6 points to 23 percent.

Recent state and district polling was light and mostly one-sided. Saint Anselm College, polling 1,411 New Hampshire likely voters August 17-18, had Chris Pappas at 49 percent and Scott Brown at 37 in the Senate race; the same pollster had Democrats up 50-35 in New Hampshire's 2nd District among 701 likely voters. J.L. Partners found Tom Cotton at 51 percent to Hallie Shoffner's 35 in Arkansas, from 803 likely voters August 14-18, and Republicans ahead 50-40 in New York's 21st District, from 500 likely voters August 15-17. Deep Root Analytics had the Minnesota Senate race 50-45 for the Democrat among 597 registered voters, August 17-18. In Idaho, The Bullfinch Group put independent Todd Achilles at 38 percent and Republican Jim Risch at 33 among 608 likely voters, August 16-19, a close result.