Anyway the only way I could see this happening is if so many Democratic-leaning people move into Idaho and Wyoming that the composition of the state changes. The current population of those two states is never going to vote Democratic.
Yep. People here never like this answer, but that is how most states change. For example, right now young Virginians and Virginians who moved there from other states vote MUCH more Democratic than older and native Virginians, but it's apparently more appealing to focus solely on NOVA "switching parties" because the Republicans are "crazy" and stuff like that. It's never the only explanation, but it always plays a big role. The South quite simply got more Republican as more Northern conservatives moved there, period. Vermont got more Democratic as more liberals moved in from NY/MA/CT/etc., period. Colorado got more Democratic as more outsiders and Hispanics moved in, period. The list goes on.
You're right about Virginia. Its leftward trend is largely based on demographic shifts. In fact, Virginia is actually a state where suburban growth (in NOVA) relative to the rural areas has helped Democrats beautifully.
