New Hampshire Senate eases to 81 for Pappas without new polling

Our model now gives Chris Pappas an 81 in 100 chance in the New Hampshire Senate race, down from 95% in our run of August 24 at 4:30 p.m. ET. That is a drop of 14.3 points of Democratic win probability over seven days, toward Republican Scott Brown, whose chance we put at 19%.

The mean margin barely moved. Our previous run had the race at D+11.0; this one has it at D+9.8. What changed is the spread around that center. A week ago our 5th-to-95th-percentile range ran from Even to D+21.8. It now runs from R+9.1 to D+28.6, which puts meaningful Republican outcomes inside the interval for the first time this month. Almost all of the probability shift is accounted for by that widening rather than by a new central estimate.

No poll of this race in our data was fielded after August 24. The most recent surveys we have are a University of New Hampshire poll for 7News of 1,846 likely voters, fielded August 20-24, which had Pappas at 45% and Brown at 40%, and a companion version against an unnamed Republican that had the Republican at 45% and Pappas at 43%; and a St. Anselm poll of 1,411 likely voters, fielded August 17-18, with Pappas at 49% and Brown at 37%. All three predate the earlier run. So the movement is the model's own, and we are not going to attach a cause to it that the payload does not support.

The race matters to the national picture. Our model gives Democrats a 49% chance of Senate control and a mean of 50.2 seats, against the 51 they need; Republicans need 50, because the vice president is a Republican and a 50-50 tie goes to them. Sixty-four days remain until the November 3 election.