Our Iowa Senate estimate moves 13 points toward Turek in a week

Our forecast of the Iowa Senate race has moved toward the Democrat, Josh Turek. On September 7 our model gave him a 33% chance against Republican Ashley Hinson. As of the run dated September 14 at 12:32 AM ET, it gives him a 46 in 100 chance. That is a shift of 12.7 points of win probability over seven days.

The expected margin moved less. Our model now puts the mean result at R+0.6, against R+2.7 a week ago. The 5th–95th percentile range runs from R+10.6 to D+9.3, which is to say our model does not distinguish between the two outcomes with any confidence.

Four surveys sit in the window. A Global Strategy Group poll of 800 likely voters, fielded August 27-31, had Turek at 46% and Hinson at 42%, with 6% for others. YouGov, fielding September 3-8, released three samples: 43% Hinson to 44% Turek among 2,166 registered voters, 43% to 47% among 2,041 likely voters, and 43% to 45% among 2,127 likely voters. None of those gaps is wide enough to establish a leader; taken together they describe a close race in a seat with no incumbent on the ballot, held by Republican Joni Ernst.

We have already written about each of those polls as they arrived. What is new here is the cumulative effect: a race our model treated as leaning Republican a week ago is now close to even, with Hinson at 54%.

Iowa matters to the national picture. Our model puts the Democratic chance of Senate control at 50 in 100, with Democrats needing 51 seats and Republicans 50, since the vice president is a Republican and a 50-50 tie goes to the Republicans. Our mean Democratic seat count is 50.3.