Whenever Democrats mismanage their own campaigns and fail to get reelected is takes about thirty seconds for them to start blaming Progressives for their own failure.

Surely, Hillary could have won in 2016 if she had campaigned for the votes of white working men in the so-called "Blue Wall" states. But why didn't she do that? Blaming generic ineptitude misses the point. She would have campaigned for those votes if she weren't instead pounding the indentitarian drum favored by Progressives and, I believe, the candidate herself. She was running to break the glass ceiling, not to save the roof over workers' heads.

Progressive positions get hung around the necks of moderate Democrats whether those Democrats espouse those positions or not. Voters assume that the governing majority of a moderate Democrat will include Progressives. Naturally, then, anyone who fears Progressives fears all Democrats. Thus, by their mere association with the Democrats, Progressive hurt the Democrats. (I agree that the Progressives are a separate "party," but so, too, are the Never-Trump Republicans, who, like the Progressives, are constrained by our two-party system.)

Lyndon Johnson famously said he'd rather have his opponents inside the tent pissing out then outside it pissing in. Not a bad default position, but it does matter whom those opponents are pissing on (and whom they're pissing off).