Kansas Senate odds tighten toward Marshall as our range narrows

Our model now gives Democrat Adam Hamilton a 4 in 100 chance of winning the Kansas Senate race, down from 15% in our September 1 run. That is a drop of 10.3 points of Democratic win probability over seven days, all of it toward Republican incumbent Roger Marshall, who is now at 96%.

The mean margin moved the other way, if only slightly. Our September 1 run put the expected result at R+12.0; this run puts it at R+10.6. What changed more is the spread around that center. A week ago our 5th-to-95th percentile range ran from R+30.6 to D+6.6, wide enough to include a Hamilton win. It now runs from R+20.8 to R+0.5, which keeps the Republican ahead across that interval. A narrower distribution centered about ten points from parity leaves less room on the Democratic side, and that accounts for the direction of the probability even with the center of the estimate a shade closer.

The payload contains one Kansas poll, and it predates the earlier run. Global Strategy Group, for the People Over Politics Action Fund, surveyed 800 likely voters August 12-16 and found Hamilton at 44%, Marshall at 43% and other candidates at 5% — a close race, not a lead for either candidate. That survey was already in our average when we published the 15% figure. No new Kansas polling appears in this payload since then, so we are not attributing the week's move to new survey data. The model moved; the cause is not established here.

Nationally, our model gives Democrats a 42% chance of Senate control, with a mean of 49.8 Democratic seats. Democrats need 51 seats for a majority and Republicans 50, because the vice president is a Republican and a 50-50 tie goes to their side.