Three YouGov samples put Cooper ahead by double digits in North Carolina

Three YouGov surveys of North Carolina, all fielded September 15-18, put Democrat Roy Cooper ahead of Republican Michael Whatley. Among 3,742 likely voters, Cooper led 53 to 41. A second likely-voter sample of 3,511 had it 54 to 41. Among 3,864 registered voters, Cooper led 52 to 41. Whatley's share was 41 percent in all three.

Our model now gives Cooper a 94 in 100 chance of winning the seat, with a mean margin of D+8.8. That is up from 92 percent and D+8.2 in our previous run, at 10:32 a.m. ET on Wednesday. The change is small, and the new numbers mostly confirm what the forecast already carried rather than redirecting it.

The model's margin remains well short of what the YouGov polls show. Our 5th-to-95th percentile range runs from R+0.7 to D+18.3, so a narrow Whatley win is inside the range our simulations produce, at the low end. The three surveys share a field period and a pollster, which limits how much independent information they add: they are close to one reading, not three.

The seat is open; the incumbent, Republican Thom Tillis, is not on the ballot. Nationally, our generic-ballot average stands at D+8.1 across 30 polls from the past 45 days. Our model gives Democrats a 55 percent chance of Senate control, with a mean of 50.7 Democratic seats. Democrats need 51 seats for control and Republicans 50, because the vice president is a Republican and a 50-50 tie goes to the Republicans. North Carolina is one of the races that makes the difference between those two numbers, which is why a two-point move here matters more than its size suggests.

Election day is November 3, 41 days out.