For the record i am going to affirm zymurgy position above but refuse the label as "contempt for the left" as it is "Contempt for what the Dem party had become" which was a centrist corporatist party, speaking to the left while serving the wealthy and corporate donors.
Yes they were still to the 'left' of the republicans but that does not mean they were 'progressive' or 'populist' in their actual positions outside a few scant movements (ACA).
What we saw for decades was 'Dem politicians decry the right' and with examples of decrying tax cuts put in when republicans took power BUT NEVER even trying to reverse them once in. They allowed almost every change to stand empowering corporations, empowering the power of oligarchs, etc, etc with a strong scolding but no action.
Trump recognized it and Bannon recognized it prior. The most dangerous political position in America (and is still) is a person and party who would unite Trumps populist right with Bernies populist left, with themes of 'America First... investments directed at the people... taking power from the rich and corporations... disrupting the status quo, with a true focus of addressing the pains of the middle and lower class'.
If a politician and party ran on that and MEANT IT, and implemented it, they would have the biggest support base for election for decades to come. A new era of reconstruction.
I thought for a moment when Trump ran on EXACTLY that messaging and won, even though it was all based on lies, that the Dems would see it and embrace it and shift that way. Instead we instantly saw, what we always see which is the corporate Dems (Pelosi wing) supported by corporate media, all repeating the same message and that is 'for Dems to win they MUST NOT move to the left and towards the populist progressive base', they call THAT the mistake of the past. While laughably acknowledging in their next breath that is exactly how Trump won, by shifting his perception that he was a populist leftist along the lines of Bernie.