It has ranged from:
* Bernie Sanders (second pick for Democrat candidate)
* James Comey (former FBI Director)
* Huma Abedin (deputy chief of staff for Clinton Campaign)
* Russian hackers
* Vladimir Putin (President of Russia)
* Wikileaks (ie: more Russian hackers)
* the Benghazi Committee
* the "Basket of Deplorables" (ie: white America)
* white women (ie: 53% of white women voted for Trump)
* white men (ie: universally reviled by progressive supremacists everywhere)
It seems the Democratic Party will never recover as it is more fragmented than ever, with ailing Nancy Pelosi and out-of-touch NYC urbanite Chuck Schumer being the only notable Democrats as of late. All they can do is respond with righteous indignation rather than form a coherent party platform, especially given extremists of all flavors left-of-center being unable to form anything beyond a rickety coalition under shredded banner of "Democrat."
Self-reflection and soul-searching is totally beyond the left's comprehension.
Clinton was just an awful candidate and the shrieking of the liberal media -- from WaPo to CNN to has-been celebrities -- was (and continues to be) tasteless. Whether Clinton's campaign was ever more than "shame on everybody that won't vote for me, also it's a woman's turn now" is irrelevant because that was the only message that got out there.
I would love to see a candidate campaign on, specifically, "tolerance, shared responsibility, and mutual respect." The Democratic Party has truly abandoned tolerance, shared responsibility, and mutual respect, and returning to it would go a long way to bridging the ever-widening gap between Democrats and Republicans.