Vox has an excellent article describing how party and electoral politics has been evolving in United States past few decades, but there are some points worth adding.
One significant factor that seems to receive little attention, but emphasized in the articles by Vance and Hochchild I had linked to earlier is the linkage between availability of “lifelines” and a sense of intergroup competition. The states that saw large increases in foreign populations that also heavily for Romney in 2012 tend to be very ungenerous in provision of lifelines, and most likely, became even stingier from 1990s on (Granted, this is basically an explanation for why MN did not flip.) In other words, in these states, the poor whites were facing even greater competition for the few lifelines that they had, not only in terms of government aids, but also in terms of reasonably secure jobs for low-skill, low-education workforce offering decent wages. The population change interacted with the economic shock to produce the backlash.
In other words, I don’t think the economic and social dimensions are necessarily orthogonal. Far from it, they interact (and mutually reinforce) each other. As long as the economic focus remains on limiting the supply of lifelines–i.e. as long as the neoliberal consensus remains the presumed “Truth”–the racialized competition for the lifelines can only intensify. The deadlock can be broken if the economic opportunities open up, both in terms of jobs and the lifelines for the luckless. While it will not turn the “rednecks” to paragons of tolerance, it will certainly abate their hostility to their “otherly” competitors.