Maine moves back to 56 percent for Jackson after UMass Lowell poll

A University of Massachusetts Lowell Center for Public Opinion/YouGov survey of 650 likely voters, fielded August 28 to September 14, puts Democrat Troy Jackson at 48 percent and Republican Susan Collins at 43 percent.

Our model now gives Jackson a 56 in 100 chance of winning the seat, up from 51 percent in our previous run earlier today. The mean projected margin moved from D+0.1 to D+0.9. The distribution is essentially unchanged in width: our 5th-to-95th percentile range runs from R+8.5 to D+10.4, against R+9.3 to D+9.6 before. That is a small shift in a race our numbers have described as close for weeks, not a new picture of it. Outcomes from a mid-single-digit win for either candidate remain well inside the range our simulations produce.

The Maine forecast has been among the most movement-prone in our model this month, and this update fits the pattern: one new survey, a few points of probability, no change to the basic shape. A 44 percent chance for Collins is not a long shot.

Maine matters for the chamber. Our model has Democrats at 52 percent to win Senate control, with a mean of 50.5 Democratic seats; Democrats need 51 seats for a majority and Republicans need 50, because the vice president is a Republican and a 50-50 tie goes to the Republicans. On that math, the Senate is close to even and a one-seat state like Maine carries most of its weight directly. Our national generic-ballot average, drawn from 30 polls over the past 45 days, stands at D+8.3. In the House, our model gives Democrats a 98 percent chance of a majority, with a mean of 245.9 seats against the 218 needed.