Interesting, because currently it's one of the bluest states in the US.
Only on a presidential level, and as shown above (see North Dakota) that can be totally decoupled from House (or Senate) voting record.
The impression I get with US House and Senate is that incumbency often means a lot more than party, I think because seniority makes a real difference under the US political system, so a significant number of people would rather have a bigger voice for their state by keeping their senator/representative with high seniority rather than have to start again with a new person, even if their sitting guy is from the other party to the one they prefer. You see seats swinging far more than they would in other countries, like an over 20-point swing in one cycle, just because the old guy has retired and so everyone has 'reset' their voting preferences to more like what they're now voting on presidential level. Or at least that's my reading of it.