I hope the progressive caucus does push the party to the left

And I think we're poised to see exactly that. I don't think it can even be avoided.The Green New Deal is brand new, give it some time to mature, Monsieur Firebrand, before calling for a pound of flesh from the wiley old politicians who know how to get things done.
Exciting times are coming after the dark Trump years are done.
"Be yourself; everyone else is already taken." Oscar Wilde