Common Cause-sponsored poll finds Cooper up eight, close to our North Carolina average

An Opinion Diagnostics survey sponsored by Common Cause North Carolina, fielded September 17-20 among 857 likely voters, found Democrat Roy Cooper at 52 percent and Republican Michael Whatley at 44 percent in the race for the open Senate seat held by Republican Thom Tillis.

That eight-point gap sits close to what our model already expected. Our projected mean margin is now D+8.7, compared with D+8.8 in the run an hour earlier. The poll confirmed the existing picture rather than changing it.

Our model gives Cooper a 94 in 100 chance of winning the seat, the same as in the previous run, and Whatley 6 percent. The model's range of outcomes also barely moved. Its 5th-to-95th percentile band now runs from R+0.8 to D+18.1, against R+0.6 to D+18.2 before. The low end of that range still includes a narrow Whatley win, which is why the chance is not higher.

Nationally, our model gives Democrats a 56 percent chance of Senate control and Republicans 43 percent. Democrats need 51 seats for control. Republicans need 50, because a 50-50 tie goes to the Republican vice president. Our model's average outcome is 50.8 Democratic seats, which puts North Carolina among the races that shape the math for control.