Model has Democrats at 93 in 100 for the House, 48 percent in the Senate

Seventy-four days from the November 3 election, our model gives Democrats a 48 percent chance of winning Senate control and a 93 percent chance of winning a House majority, as of 6:30 AM ET on August 21. Democrats need 51 Senate seats for control and Republicans need 50, because the vice president is a Republican and a 50-50 tie goes to the Republicans. Our mean outcome in the Senate is 50.1 Democratic seats, short of the 51 required. In the House, where 218 seats make a majority, our mean is 242.3 Democratic seats, and the chance of a Democratic majority works out to 93 in 100. Our generic ballot average stands at D+6.7, drawn from 24 polls fielded in the past 45 days.

One note on the House number. Our simulation draws error at four correlated levels: national, census division, state, and each district on its own. It does not include a term linking demographically similar districts in different parts of the country, because we have no cluster data for this run. That omission makes our House control probability marginally firmer than a fuller model would produce. We have not measured the size of the difference, so we are not adjusting for it.

The largest overnight move in our forecast was the Michigan Senate race, where the Democratic win probability rose 15.1 points, to 58 percent from 43 percent. A Susquehanna Polling & Research survey of 800 likely voters, fielded August 11-17, had Abdul El-Sayed at 46 percent and Mike Rogers at 39 percent. Elsewhere, our estimate of Democratic chances in the Louisiana Senate race fell 8.4 points to 1 percent, and in Ohio's 7th District it fell 5.9 points to 62 percent. Our Maine and Ohio Senate estimates and our AR-2 forecast also moved; those shifts are covered separately.

In recent polling, Saint Anselm College surveyed 1,411 New Hampshire likely voters on August 17-18 and found Chris Pappas at 49 percent to Scott Brown's 37 percent; the same pollster's survey of 701 likely voters in NH-2 over the same two days had the Democrat at 50 percent and the Republican at 35 percent. InsiderAdvantage, polling 800 Georgia likely voters on August 16-17, had Jon Ossoff at 50 percent and Mike Collins at 43 percent. KTSP/SurveyUSA, polling 661 Minnesota likely voters on August 13-17, had the Democrat at 46 percent and the Republican at 41 percent. J.L. Partners had Tom Cotton at 51 percent to Hallie Shoffner's 35 percent among 803 Arkansas likely voters, fielded August 14-18, and the Republican at 50 percent to the Democrat's 40 percent in NY-21 among 500 likely voters, fielded August 15-17. A Global Strategy Group survey of 500 likely voters in MI-7, fielded August 11-13, had the Democrat at 49 percent and the Republican at 47 percent, a close race.

Idaho's two most recent Senate polls disagree. The Bullfinch Group, surveying 608 likely voters August 16-19, had independent Todd Achilles at 38 percent and Jim Risch at 33 percent. Peak Insights, surveying 500 likely voters August 11-13, had Risch at 52 percent and Achilles at 18 percent.