The Washington Post has a great breakdown of the new Suffolk poll and its implications for the Democratic primary race. Most notably the drop in favorability among black voters -16 since July and +31 for Sanders. While Clinton's decline in support from black voters in primary matchups can largely be traced to Joe Biden drawing votes from her, the drop in favorability among black voters can't easily be pinned down though. Suffolk is not the only pollster to find this Quinnipiac found her net favorability rating among black voters going from +77 to +62 from August to September. PPP seemed to tell the same story Clinton went from +74 in July to +55 in September with black voters in terms of favorability. Black voters seem to be liking Hillary Clinton less and less and this is supposed to be her base of support.
SUFFOLK POLL (WASHINGTON POST)
QUINNIPIAC POLL AUGUST TO SEPTEMBER
PUBLIC POLICY POLLING JULY TO SEPTEMBER