Seems really simple to me: don't discuss literally everything BUT the concerns of poor white folks? Trump is full of shit but at least he lies TO the majority population. The Dems either ignore, talk down to or dismiss the majority of their constituents. When you make literally every talking point about marginalized groups or the Ukraine or whatever you have no chance of convincing someone to switch to your side because you underline that their concerns are not a priority or even on your radar.

If you spend a quarter of your time discussing transgender athletes or unisex bathrooms 99% of people don't have a personal stake in that. In other words, the Dems aren't doing the fundamental job of politicking, which is to engage with their constituents on the topics that matter to them directly.