I’ve never been there, but have heard that Montana politics has some unique elements, and that Montana Democrats aren’t nearly as liberal as those in other places.
But this is where it’s good to nationalize these elections. A vote for Jon Tester is a vote for Chuck Schumer as majority leader. A vote for any Democrat House candidate is a vote for Nancy Pelosi as speaker, etc.
Tester IS as liberal as Democrats in other places.
Tester is hard left. For example his 2017 rating by the ACU is 96% left. A vote for Tester is not just a vote for Tester's Schumer vote. It's a vote for his entire 96% liberal voting record.