The first "shift to the left" the democrats have had since LBJ was Bernie Sanders's influence on the platform last year - and even if Bernie had won the democrat platform would STILL be to the right, economically, of where it was under Wilson or FDR - that was the party of  The Trustbusters.

That party is long gone. In the past 40 years through 3 democrat presidents only ONE company was ever prosecuted for antitrust violations and they got off with a slap on the wrist. Clinton wrote a welfare reform act that singlehandledly increased extreme poverty in the USA by 30%. The democrats were a lot of things in the past 30 years -but they weren't leftwing, not even slightly.

They were rightwing, just SANE rightwing- while the republicans responded by going to CRAZY rightwing.
It's only now, in 2017 that, for the first time in decades, the progressive voters of the democratic party has actual policy influence.