Maine model moves again toward Jackson, now 90 percent

Our model now gives Troy Jackson, the Democrat, a 90 in 100 chance of winning the Maine Senate race against Republican incumbent Susan Collins. A week earlier, in our August 21 run, the figure was 82 percent. That is a move of 8.1 points of Democratic win probability over seven days.

The mean margin moved with it. Our model's expected result went from D+6.1 on August 21 to D+8.5 now. The 5th-to-95th-percentile range narrowed and shifted: from R+4.8 to D+16.7 last week, to R+2.3 to D+18.7 today. Republican outcomes remain inside the distribution at both ends of that week, but they occupy less of it.

There is no new Maine polling in this payload. That was also true of last week's run, and it is the second consecutive week our estimate has moved in the same direction without survey data attached to it. We are not going to assign a cause we cannot document. What we can say is that the race sits inside a national picture in which our generic-ballot average, drawn from 23 polls over a 45-day window, stands at D+6.6.

Control of the Senate remains closer than this seat. Our model gives Democrats a 45 percent chance of winning a majority and Republicans 55 percent, with a mean of 50.0 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. A 90 percent chance is not a result, and the 10 percent side of it is where a Collins win lives.