The American public is deeply, deeply stupid. The only theory of change that hasn't been refuted is just vibes. Do and campaign on popular things doesn't work, unpopular things doesn't appear to hurt you so long as your vibe is normal. Shit sucks.
The GOP have a media echo system that Dems never will. The so called liberal media have no problem throwing Dems to the wolves to "prove" that they're not liberal, to which no one is convinced.