And the people who actually control the party, decide what legislation gets a vote, and punish members who go against leadership will never allow it to happen, nor will they allow any of those progressive politicians to succeed them in their positions of power. Progressives are allowed on the party bcs they help keep the left flank in line, but they will never be allowed to hold any real power. That might threaten the Wall St donation gravy train, and the Third Way Foundation assholes who have a death grip on the power structures of the party will kill everyone on Earth before they give up that money.