Party-line voting mentalities
"Red or Dead"
"Blue no matter who"
...tend to be far less effective at local and state levels than they do at federal levels. Attentiveness to the regional component of politics becomes much more important the more regionally compartmentalized the election is.
Just because a state is a "Blue/Red" state in a federal election (where there's a wide chasm in terms of policy positions) doesn't mean that that they're on board with everything.
For instance, in a state that's "just a touch left of center" could very well be closer to a centrist republican than they are to a far left democrat (despite technically being on the same side of the imaginary bisecting line)
That's basically how you end up with outcomes like this for places like Maryland:
At the federal level:
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At the state level:
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(Massachusetts and New Hampshire are both the same story...they're also states where Democrats dominate at a federal level, but who have Republican governors who've been winning handily for multiple state election cycles)
If it can happen in much more left-leaning places like New England states, it'd have to sheer hubris on the part of Democrats to think it wouldn't be possible in more moderate (or even center-right) areas like Virginia.
Preferring an Obama over Romney, or preferring Hillary over Trump doesn't equate to "I'll take any democrat over any republican". Hopefully this was a valuable learning experience.