InsiderAdvantage puts Cooper up about six, and our model moves to 94 percent

An InsiderAdvantage survey of 1,200 likely voters in North Carolina, fielded September 16-17, puts Democrat Roy Cooper at 48.4 percent and Republican Michael Whatley at 42.5 percent, with 1.6 percent for other candidates. That is a Cooper lead of about six points.

Our model now gives Cooper a 94 in 100 chance of winning the open seat, up from 92 percent in the previous run earlier this morning. The mean projected margin moved from D+8.3 to D+9.1, and the 5th-to-95th percentile range narrowed slightly, from R+1.6 to D+18.0 to a span of R+0.6 to D+18.8. The model still allows for a Republican win in roughly 6 percent of simulations.

The new poll is narrower than the margin our model expects, and it did not pull the forecast down. That is worth saying plainly: the change in this run is small, and the direction of the race in our numbers is the same as it was before the poll landed. Whatley's 42.5 percent is the Republican's share in one survey of one electorate; our forecast blends polling with the rest of its inputs, and a single result at six points sits inside the range it already treats as ordinary.

The seat matters to the national picture. Our model gives Democrats a 52 percent chance of Senate control, against 47 percent for Republicans, with a mean of 50.5 Democratic seats. Democrats need 51 seats for control; Republicans need 50, because the vice president is a Republican and a 50-50 tie goes to them. On the generic congressional ballot, our average of 28 polls over the past 45 days stands at D+7.4. Forty-six days remain before the November 3 election.