Why is Tester doing so much better than Heitkamp?

[Stranger in a strange land]

Tester:

1) Is a better candidate
2) Is more likable, relatable, and charismatic (watch the ads he records at his farm)
3) Is male (sorry but it matters. It obviously shouldn't, but it does)

And also, ND has had a huge influx of oil workers over the last six years, and MT hasn't had anything comparable.