Close InsiderAdvantage poll trims our Kansas Senate odds for Hamilton to 56 percent

A new InsiderAdvantage survey of 1,200 likely voters in Kansas, fielded October 13-14, found Republican Sen. Roger Marshall at 48 percent and Democrat Adam Hamilton at 47 percent. A one-point gap of that kind is a close race, not a lead for either candidate.

The poll moved our forecast. Our model now gives Hamilton a 56 in 100 chance of winning the seat, down from 62 percent in our run earlier this morning. Marshall's chance rose to 44 percent from 38 percent. Our model's expected margin narrowed to Hamilton by 0.9 points, from 1.6 points before the poll was added.

The change is modest, and the uncertainty around it remains wide. Our model's 5th-to-95th percentile range for the result now runs from Marshall by 7.7 points to Hamilton by 9.4 points. That range shifted slightly toward the Republican with this poll. Earlier it ran from Marshall by 7.0 to Hamilton by 10.1.

Kansas matters to the national picture. Our model gives Democrats a 61 percent chance of winning Senate control, with a mean outcome of 51.0 Democratic seats. Democrats need 51 seats for control and Republicans need 50, because the vice president is a Republican and a 50-50 tie goes to the Republicans. Our generic ballot average, built from 37 polls over 45 days, stands at Democrats plus 8.2 points.

With 18 days until the November 3 election, our model still rates Hamilton as a slight favorite in Kansas. The new poll narrowed that edge.