Minnesota Senate poll shows Democrat up five, and our forecast eases slightly

A KTSP/SurveyUSA survey of 661 likely voters in Minnesota, fielded August 13-17, puts the Democrat at 46 percent and the Republican at 41 percent. The poll leaves about 13 percent of likely voters unaccounted for between the two parties. No margin of error is attached to the numbers we have, and a five-point gap in a sample that size is narrow enough that the safer description is a race the Democrat leads modestly rather than comfortably.

Our model now gives the Democrat a 91 in 100 chance of winning the seat, with a mean margin of D+9.0 and a 5th-to-95th percentile range running from R+1.9 to D+20.0. That is a small step back from our previous run, at 12:30 a.m. ET on August 19, which had the Democrat at 95 percent, a mean margin of D+10.8 and a range from R+0.3 to D+21.7. The new poll trims the expected margin by close to two points and widens the plausible Republican outcomes at the low end.

The direction of the change matters more than its size. This is an open seat — Tina Smith, the Democratic incumbent, is not part of our candidate list — and our model still treats it as a Democratic-leaning race well clear of a toss-up. One poll of 661 voters moved the forecast by four percentage points of win probability, which is what a single fresh number should do in a race with a lead this wide.

Nationally, our average of 25 generic-ballot polls over the last 45 days stands at D+6.7. In the Senate, we give Democrats a 47 percent chance of winning control and Republicans 53 percent, with a mean of 50.1 Democratic seats. Democrats need 51 seats for a majority; Republicans need 50, because the vice president is a Republican and a 50-50 tie goes their way.