But I think this article from Jacobin is well worth a read if you haven't, a postscript of Bernie's 5 Year War. https://jacobinmag.com/2020/08/bernie-sanders-five-year-war Here's the section on the black vote.

Struggling to Win Black Voters
After the 2016 campaign, in which Sanders’s struggles with black voters cost him dearly, the 2020 campaign made a range of well-documented efforts to court African Americans, in both substance and style. The goal, as Adolph Reed Jr and Willie Legette have argued, was never to win a singular, homogenous, and mythical “black vote” — but in order to compete in a Democratic primary, Sanders did need to convince a lot more black voters.

In 2019, the campaign released an ambitious plan to fund historically black colleges and universities; supported by scholars like Darrick Hamilton and leaders like Jackson, Mississippi, mayor Chokwe Antar Lumumba, Sanders railed against the racial wealth gap and delivered substantive plans to close it. His campaign poured resources into South Carolina, which Sanders visited more times than Joe Biden or Elizabeth Warren; Bernie himself went on The Breakfast Club and said his 2016 campaign had been “too white.”

None of it seemed to make an appreciable difference. In South Carolina, where Sanders won 14 percent of black voters in 2016, exit polls showed him winning 17 percent in 2020. In the state’s five counties with a black population over 60 percent, Sanders increased his vote share from 11 percent to 12 percent.

It was no better for him on Super Tuesday and beyond. In the rural South, from eastern North Carolina to western Mississippi, Sanders struggled to break the 15 percent threshold in majority-black counties. In some black urban neighborhoods, like Northside Richmond and Houston’s Third Ward, he made small gains on his 2016 baseline, occasionally winning as much as a third of the vote; but in others, like Southeast Durham and North St. Louis, Sanders fared even worse. On the whole, Biden clobbered him just as comprehensively as Clinton had four years earlier.

After 2016, it was still possible to argue, optimistically, that black voter preferences reflected Clinton’s advantage in name recognition and resources, along with Sanders’s need to focus on the early contests in Iowa and New Hampshire. All the best survey data showed reliable and enthusiastic black support for the core items on Bernie’s social-democratic agenda. With improved messaging and a more serious investment in voter outreach, surely an insurgent left-wing candidate could breach the Democratic establishment’s “firewall” and win a large chunk of black voters.

Bernie Sanders was not that candidate, either in 2016 or in 2020. But after years of struggle, it is time to revisit the assumption that superior policy, messaging, and tactics are enough for any insurgent to overcome black voter support for establishment Democrats. After all, Sanders is far from the only left-wing candidate who has struggled on this front.

In the 2015 Chicago mayoral election, Rahm Emanuel beat Chuy García with huge margins among black voters; the same pattern was visible in gubernatorial races in Virginia, New Jersey, Michigan, and New York, where black voters overwhelmingly backed Ralph Northam, Phil Murphy, Gretchen Whitmer, and Andrew Cuomo against progressive outsiders. In last year’s race for Queens district attorney, Melinda Katz barely edged past Tiffany Cabán with the strong support of black voters in Southeast Queens.

Nor have anti-establishment black candidates necessarily fared much better with black primary voters. Jamaal Bowman’s recent victory over Eliot Engel is a meaningful and inspiring win for the Left, but not many left-wing candidates have had the advantage of facing a severely out-of-touch white opponent in a plurality-black district. Far more often, under different circumstances, the result has gone the other way. In the 2017 Atlanta mayoral race, the business-friendly party favorite Keisha Lance Bottoms creamed Vincent Fort, who had been endorsed by both Bernie Sanders and Killer Mike. And in congressional contests from St. Louis and Chicago to Columbus, Ohio and Prince George’s County, Maryland, black progressive insurgent campaigns have failed to catch fire, with black voters ultimately helping establishment-backed incumbents coast to victory at the polls.

Black voter support for mainline Democrats is a broader trend in American politics — a trend approaching the status of a fundamental fact — and it cannot be explained with reference to Bernie Sanders alone.

After 2016, some argued that a clearer focus on racial justice and a concerted effort to woo activists might boost a left-wing campaign with black voters. But the 2020 race offered slim evidence for that proposition, either in Sanders’s performance or in the frustrations of the Elizabeth Warren campaign, whose platform included a prominent focus on black maternal mortality, grants for black-owned businesses, and targeted reforms to help “farmers of color.”

This rhetoric won black organizers in droves but hardly any black votes: among African Americans, exit polls showed Warren trailing not only Biden and Sanders but Bloomberg, too, in every single state, including her own. In North Carolina’s rural black-majority counties, farmers of color did not turn out for Warren, who actually received fewer votes than “no preference.”

Another popular view is that black voters have the most to fear from Donald Trump and the Republicans, and thus tend to favor moderate, conventionally “electable” candidates. But while concerns about electability surely played a key part in Bernie’s 2020 defeat, there is little evidence to suggest that it mattered more to black Democrats than white Democrats (if anything, polling suggests the opposite). Fear of general election defeat also cannot explain why black voters favored Joe Crowley over Alexandria Ocasio-Cortez, Andrew Cuomo over Cynthia Nixon, or establishment leaders in other deep-blue areas where Republicans are banished from politics altogether.

Nor can the phenomenon be explained by actual ideological conservatism, or any real hesitance to get behind a politics of material redistribution. In fact, black voters support Medicare for All at higher rates than almost any other demographic in the country.

The institutional conservatism of most black elected leaders, on the other hand, continues to stack the deck against left-wing politics. Powerful black politicians like Jim Clyburn and Hakeem Jeffries, as Perry Bacon Jr has argued, support the establishment because “they are part of the establishment.” The Congressional Black Caucus has not tried to disguise its fierce hostility to left-wing primary challenges, even when the progressive challengers are black, like Bowman and Mckayla Wilkes, and the centrist incumbents are white, like Engel and Steny Hoyer.

Overcoming the near-unanimous opposition of black elected leaders is difficult enough, but the problem for left-wing insurgents is even greater: it’s hard to win black voters by running against a party establishment whose preeminent figure is still, after all, America’s first black president. In the age of Obama, as Joe Biden’s primary campaign showed, black primary voters may well be moved more by appeals to institutional continuity than either personal identity (as Kamala Harris learned) or political ideology.

After fifty years of living in a system where profound material change seems almost impossible — and black politics, like many other zones of politics, has become largely affective and transactional as a result — that feeling is understandable. Black voters, of course, must be a critical part of any working-class majority. But as long as every black political figure with significant institutional standing remains tied to Obama’s party leadership, and remains invested in using that tie to beat back left-wing challenges, anti-establishment candidates will face tough odds.

If there is hope for the Left here, it is that black support for establishment Democrats remains tenacious rather than enthusiastic — strong support from a relatively small group of primary voters. Campaign boasts and press puffery aside, there was no black turnout surge for Joe Biden. Across the March primaries, even as overall Democratic turnout soared in comparison to 2016, it dropped absolutely in black neighborhoods across the country.

In Michigan, Democratic participation bloomed by more than 350,000 votes but wilted in Flint’s first and second wards, where turnout declined from over 25 percent of registered voters to under 21 percent. Similar declines from 2016 were recorded in Ferguson, Missouri, in North St. Louis, in Houston’s Kashmere Gardens, Sunnyside, and Crestmont Park, and in Southeast Durham — even as statewide Democratic turnout soared in Missouri, Texas, and North Carolina.

This follows a pattern already evident in the 2016 general election, in which poor and working-class black voters — like working-class voters generally — appear to comprise a smaller and smaller share of the active Democratic voting coalition.

That is no consolation for Bernie Sanders, whose campaign was premised on its ability to help generate working-class participation in politics. But it does suggest that in some ways, the Left’s struggles with black voters are a specific symptom of a more general disease. The Sanders campaign, in both its remarkable strengths and its ultimately fatal weaknesses, illuminated the larger problem that has plagued left politics across much of the developed world: a failure to mobilize, much less organize, the majority of workers.