Michigan is dead for the GOP.
That's a rather odd claim, since the GOP controls all statewide executive positions, both chambers of the state legislature safely, and a 9-5 majority in the House election. Although it does typically lose Senate and presidential elections, those are the only ones. The Republican Party is, on balance, probably the stronger of the two in Michigan.
With that said, it probably doesn't make much sense for the Republican Party to make Stabenow a target in 2018 when there's so much lower-hanging fruit, and she probably won't be challenged
too seriously. But that doesn't mean the MIGOP isn't quite strong.