Its hard, even impossible, to have a “single narrative” when your electoral base is made up of competing special interest groups that are increasingly at odds with each other over all sorts of major issues.
The Dems are all over the map because their coalition is all over the map. AND, thanks to new media, they can’t really get away with saying different things to different groups and having no one be the wiser for it.
The GOP can be blamed for failing to even try to exploit those faultlines.