Maine forecast eases to 58 percent for Jackson after tied Quantus poll

A Quantus Insights survey of 621 likely voters in Maine, fielded September 14-15, puts Susan Collins at 47.6 percent and Troy Jackson at 47.4 percent. That gap is two-tenths of a point. On its own, the poll says the race is close and nothing more precise than that.

Our model now gives Jackson a 58 in 100 chance of winning the seat, with Collins at 42 percent. Before this run, our forecast had Jackson at 75 percent. The mean margin moved from D+4.1 to D+1.2, and the middle of our distribution narrowed around a near-tie: the 5th-to-95th percentile range is now R+8.6 to D+11.1, against R+5.7 to D+13.9 in the prior run.

The direction is the same one our earlier notes described this month; the size of the move is the new part. A single poll of this size does not normally carry a forecast 17 points, and the shift reflects how little daylight there was between the two candidates in it relative to what our average had been carrying.

Maine matters to the chamber arithmetic. Our model gives Democrats a 49 percent chance of Senate control and Republicans 50 percent, with a mean of 50.2 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 the Republicans. A seat priced at close to even odds, in a chamber priced at close to even odds, is where most of the remaining uncertainty sits.

Nationally, our generic-ballot average stands at D+7.3 across 26 polls over the past 45 days. Maine is running well to the right of that average in our estimates. Forty-eight days remain before the November 3 election, and one poll is one poll.