Generic ballot average sits at D+6.6 with 67 days to the election

Our generic ballot average stands at D+6.6, drawn from 23 polls fielded over the past 45 days, as of 6:30 AM ET on August 28.

In the Senate, our model gives Democrats a 45 percent chance of winning control and Republicans 55 percent. The mean outcome in our simulations is 49.9 Democratic seats. Democrats need 51 seats for control and Republicans need 50, because the vice president is a Republican and a 50-50 chamber goes to the Republicans. In the House, our model gives Democrats a 94 in 100 chance of a majority, with a mean of 241 seats against the 218 needed. One caution on that figure is ours to make: our simulation draws error at the national, census-division, state and district levels, but not for demographically similar districts scattered across different states, because we have no cluster data for it. The House number is therefore marginally firmer than a fuller decomposition would leave it.

The largest single-race move in our forecast was AK-1, where the Democratic win probability fell 73.6 points, from 74 percent to effectively zero. TX-15 moved the other way, up 19.4 points to a 55 percent Democratic chance. OH-7 slipped 9.7 points to 52 percent. Our Ohio Senate and Maine Senate estimates also shifted, as noted separately; Ohio now sits at 46 percent Democratic and Maine at 90 percent.

On the Senate polling, a University of New Hampshire survey of 1,878 likely voters, fielded August 20-24, put Chris Pappas at 45 percent and Scott Brown at 40 percent in New Hampshire. The same pollster, surveying 881 Massachusetts likely voters over the same dates, had Ed Markey at 49 percent and John Deaton at 30 percent. A Suffolk University poll of 500 Iowa likely voters, fielded August 20-23, found Ashley Hinson at 45 percent and Josh Turek at 41 percent, a close result at that sample size. An Impact Research survey of 800 South Carolina likely voters, fielded August 18-24, had Annie Andrews and the Republican tied at 41 percent apiece.

In the House, Quantus Insights polled 509 likely voters in OH-1 from August 21-24 and released several versions of the matchup. Greg Landsman led Eric Conroy by margins ranging from about three points to four across them, with his share between 46.5 and 52 percent. Two Texas districts were surveyed by Public Policy Research and Texas Southern University from August 18-22. In TX-34, with 700 likely voters, Vicente Gonzalez took 45 percent to Eric Flores's 42 percent. In TX-28, with 600 likely voters, Henry Cuellar led Tano Tijerina 45 percent to 34 percent.