Hammering on Clinton's trade agreement support didn't hurt.
Even though NAFTA was hubby's doing and she back-paddled on TPP. Anyone who had or knew someone who had a manufacturing job couldn't really trust her. That counteracted the black leadership support of Clinton.
Bernie really needed to tell and repeat the story of his minor, but at the time risky, support of the Civil Rights movement in the 1960s.
Alex
"There is a cult of ignorance in the United States, and there has always been. The strain of anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that "my ignorance is just as good as your knowledge."
-- Isaac Asimov