Maybe if progressives weren't so condescending and dismissive of people who did not agree with them totally, and tried to frame their arguments in terms that appeal to those other people, they might be more persuasive? Calling people stupid isn't exactly the best way to win them to your side, as all those "deplorables" and "Gruberites" who turned out in droves last November demonstrated.
and maybe finding issues that had more mainstream appeal than gender correctness or income inequality might help.
Income inequality is a losing argument in the heartland because secretly everyone
wants to be rich; and overplaying it as an issue means you are turning away lots of people you otherwise might attract. For the voter who thinks "I may not be rich today, but someday I hope to get there," why not demonstrate how your policies will help bring that about?
(assuming you actually
have any policies that would do that....

)