At The Atlantic, Michelle Cottle has a nice piece on the difficulty down ballot Republicans are likely to have in separating themselves from Donald Trump (if he proves to be a liability), given how much more nationalized elections have become in recent decades.  That nationalization, of course, is a reflection of how polarized and partisan politics has become, both nationally and in the states.  The piece includes this good quote:

“Ask any of the 2014 red-state Democrats from the Senate how it went when they localized their races—but you’ll have a hard time reaching them, because they’re no longer in office,” quipped a Democratic campaign operative who requested anonymity to avoid offending colleagues.