But the most palpable absence in Philadelphia was Vermont Sen. Bernie Sanders, who won over a goodly number of these activists in 2016 by challenging Hillary Clinton as a democratic socialist. Sanders sent campaign staff and top surrogate Nina Turner but didn’t address Saturday’s forum. (He’s now coming here Monday to rally with nurses seeking to save Hahnemann University Hospital.) Maybe it was personal differences with some Netroots Nation organizers, maybe it was the bitter memory of a confrontation with Black Lives Matter activists at the 2015 event, or maybe he didn’t want to call attention to the fact that a lot of his primary voters from three years ago are now swooning for Warren.