Cooper's chances in North Carolina rise to 94 percent in our model

Our model now gives Roy Cooper, the Democrat, a 94 in 100 chance of winning the open North Carolina Senate seat, up from 85 percent in our run of September 11. That is a move of 8.3 points of Democratic win probability over seven days. Michael Whatley, the Republican, is at 6 percent.

The projected margin moved with it. Our mean margin is now Cooper by 9.1 points, against 6.4 points a week ago, and our 5th-to-95th percentile range runs from Whatley by 0.6 to Cooper by 18.8. The week-earlier range extended to Whatley by 3.6, so the model now puts less of its distribution on a Republican win.

Three surveys arrived in the interval. A Trafalgar Group poll of 1,084 likely voters, fielded September 8-10, had Cooper at 48.2 percent and Whatley at 42.3. Harper Polling, sponsored by the Carolina Journal, surveyed 608 likely voters on September 13-15 and had Cooper at 49.2 percent to Whatley's 34.1. The most recent is an InsiderAdvantage poll of 1,200 likely voters, fielded September 16-17, with Cooper at 48.4 percent and Whatley at 42.5. All three put Cooper ahead, and the two larger samples agree closely on his share.

The national picture is steadier than the state one. Our generic-ballot average, drawn from 28 polls over a 45-day window, stands at Democrats plus 7.4. In the Senate, our model gives Democrats a 52 percent chance of winning control and Republicans 47 percent, with a mean of 50.5 Democratic seats; Democrats need 51 seats for a majority and Republicans 50, because the vice president is a Republican and a 50-50 tie goes to the Republicans. North Carolina is one seat in that arithmetic, and the Senate estimate has not moved as far as this race has.