New Hampshire poll narrows our NH-1 margin without changing the favorite

A University of New Hampshire survey of 707 likely voters, fielded September 17-21, puts Democrat Stefany Shaheen at 46 percent and Republican Anthony DiLorenzo at 42 percent in New Hampshire's 1st District. It is the only new number in this race, and it describes a close contest rather than a settled one.

Our model still makes Shaheen the clear favorite, at 94 percent, or 94 in 100. That is down from 98 percent in our previous run earlier on September 24. The mean margin moved with it, from D+18.9 to D+14.2, and the spread widened: our 5th-to-95th percentile range now runs from R+0.4 to D+28.9, against D+4.2 to D+33.5 before. In short, the poll did not change who leads in our estimate. It changed how much room the model leaves for a Republican win, from almost none to a small but real share of simulations.

The national picture around the district has not moved. Our generic-ballot average stands at D+8.3 across 30 polls in a 45-day window. In the House, our model gives Democrats a 98 percent chance of winning control, with a mean of 245.7 seats against the 218 needed. One caveat is ours, not the data's: our simulation draws error nationally, by census division, by state and by district, but we have no cluster data to correlate demographically similar districts across state lines. Without that term, the House control number is marginally firmer than a fuller accounting would leave it.

The Senate remains the closer of the two chambers in our forecast, at 52 percent for Democratic control and 47 percent for Republican, with a mean of 50.5 Democratic seats. Democrats need 51 seats there; Republicans need 50, because a 50-50 tie goes to the Republican vice president.