I think Booker is an irredeemable among the Sanders wing of the party.
It's a sad day for America when most progressive senator isn't progressive enough for a significant chunk of the party.
He's not the most progressive.
A) that.
B ) It's about a mix of progressivism, leftism, and populism (which is why I'm pretty careful to say prog populist when referring to Bernie types). Whatever you think about Booker's attitude on the state's role in improving life, it's really hard to argue that he's a lefty or that he's a populist.