InsiderAdvantage finds a close Iowa Senate race, and our estimate edges toward Turek

An InsiderAdvantage survey of 1,200 likely voters, fielded September 22-23, finds the Iowa Senate race close. It puts Democrat Josh Turek at 47.4% and Republican Ashley Hinson at 45.7%, with 1.6% choosing another option. That 1.7-point gap is small enough that we treat the race as close.

The poll moved our forecast only slightly. Our model now gives Turek a 62 in 100 chance of winning the open seat, up from 60% in the run earlier today. Hinson's chance is 38%, down from 40%. Our average margin moved from D+1.5 to D+1.7, which matches the gap in the new poll.

The new numbers confirm the position the race had already reached rather than changing it. Our range of plausible outcomes remains wide. Our model puts the 5th-to-95th percentile span at R+7.6 to D+11.2, compared with R+8.0 to D+10.8 before this poll. Both candidates win in a substantial share of our simulations.

The race matters for the chamber. Our model gives Democrats a 56% chance of winning Senate control and Republicans 44%. Democrats need 51 seats for a majority; Republicans need 50, because the vice president is a Republican and a 50-50 tie goes to them. Our model's average outcome is 50.8 Democratic seats, just short of the Democratic threshold, so a seat such as Iowa's sits near the center of that calculation. Nationally, our generic ballot average, built from 28 polls over 45 days, stands at D+8.3.