Harper poll puts Cooper 15 points up, and our model moves to 92 percent

A Harper Polling survey of 608 likely voters in North Carolina, sponsored by the Carolina Journal and fielded September 13-15, gives Democrat Roy Cooper 49.2 percent and Republican Michael Whatley 34.1 percent, with 2.9 percent for other candidates. That is a 15-point spread, the widest single reading in this payload.

Our model now gives Cooper a 92 in 100 chance of winning the seat, up from 84 percent in our previous run earlier on September 17. The projected margin moved with it, from D+5.8 to D+8.5. Our 5th-to-95th percentile range now runs from R+1.3 to D+18.3, against R+3.9 to D+15.6 before. The direction was already established — we had Cooper at 84 percent going into this poll — but the Harper number pushed both the central estimate and the floor upward rather than simply confirming them.

The seat is open; Republican Thom Tillis is the sitting senator and is not on our candidate list for the race. Neither Cooper nor Whatley is an incumbent.

The national picture is less settled than the state one. Our model gives Democrats a 48 percent chance of winning Senate control and Republicans 51 percent, with a mean of 50.2 Democratic seats. Democrats need 51 seats for control and Republicans need 50, because the vice president is a Republican and a 50-50 tie goes to the Republicans. So an estimate this strong in North Carolina sits alongside a chamber our model treats as close to a coin flip.

In the House, our model gives Democrats a 97 in 100 chance of reaching the 218 seats needed for control, with a mean of 243.3 seats. Our generic-ballot average is D+7.5 across 27 polls over 45 days.