I still think Marshall will win by 7-8 points. This is TN-SEN 2018 all over again.
Tennessee is your typical race-polarized socially conservative southern state. It has suburbs that stubbornly refuse to realign, an unhealthy love of culture-war red meat, an excess of religion, and a severe lack of education.
Kansas is socially moderate, lacks race-polarization, and is effectively a three-party system. A Democratic governor was elected by a comfortable margin two years ago and the Republican party is on the verge of losing its legislative supermajorities (that it never really had anyway, because, again, three-party system). It's also (slightly) pro-choice according to polls, less religious and more educated than most Republican-leaning states, and its suburbs are realigning very quickly.
This is the Republican-state equivalent of Minnesota vs. Massachusetts. Massachusetts is "more Democratic," but it's also much more likely to elect a Republican to statewide office, because Massachusetts is a pragmatic and elastic state, while Minnesota is polarized and full of partisan hacks on both sides.