Maine Senate is a coin flip again after NYT/Siena finds a close race

A New York Times/Siena University survey of 619 likely voters in Maine, sponsored by the Portland Press Herald and fielded September 15-22, put Republican Susan Collins at 48.7 percent and Democrat Troy Jackson at 45.9 percent. The gap is under three points on a sample that size, which makes this a close race rather than a lead for either candidate.

Our model now gives Jackson a 51 in 100 chance of winning the seat, with Collins at 49 percent. The previous run, at 4:32 AM ET today, had Jackson at 78 percent. The mean projected margin moved from D+4.4 to D+0.2, and the spread tightened around that new center: our 5th-to-95th percentile range now runs from R+9.4 to D+9.6, against R+5.1 to D+13.9 before.

That is a reversal of the direction this page described yesterday, when the model moved 17 points toward Jackson. The Times/Siena numbers pull the average back the other way and leave the race where the forecast has repeatedly landed over the past three weeks: effectively even, with both candidates inside the range of plausible outcomes by a wide margin. Forty days out, a projected margin of two-tenths of a point is another way of saying our model cannot separate them.

The seat matters to the chamber arithmetic. Our model has Democrats winning Senate control 50 percent of the time and Republicans 49 percent, with a mean of 50.4 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. Our national generic-ballot average stands at D+8.1 across 30 polls over the past 45 days, which is not where Maine is polling.