The belief is that most Americans (including Republican voters) are democratic socialists, they just need a True Progressive to lead and inspire them: they'll rise up in class solidarity and join the movement/revolution. The movement will force lawmakers to do the right thing. They don't do that now because they're all corrupt and beholden to wealthy donors and corporations. The True Progressive leader is not beholden, grassroots only. All dysfunction in government is due to money in politics (status quo). The pure and righteous leader will fight for The People and good will conquer evil. The end.

They seriously believe that if you just go to West Virginia or wherever and explain why people are voting against their own economic interests, the scales will fall from their eyes and they'll join the 99% against the 1%. When running for office and that doesn't work, blame the Democratic establishment stopping at nothing to defeat you -- rigging or having more money or some conspiracy (because obviously The People agree with you because you are right).

Needs a religious-like belief and faith, reality be damned. Especially in Nina Turner's case, literally religious. I wondered for a long time why she always said "Hello somebody" until I saw someone explain that it's a church thing.