Either Catherine Hanaway or Tom Schweich defeat Koster, albeit narrowly. Unless it's a very good year (or in the event of an unpopular GOP incumbent, but that's not the case) I don't think Missouri is winnable by Democrats, but they can come close and Koster is a very talented politician.
Their governor is a Democrat, and a couple of their other statewide officials are, too. And it's still a swing state in presidential elections; McCain only took it by a few thousand votes in 2008. I have a feeling there will be a lot of close gubernatorial elections in 2016, and this will be one of them.
