Biden has the support of 31 percent of black Democratic primary voters, while Sanders captures the backing of 29 percent. Aggregated data from 2019 shows that Biden led Sanders among these voters by as much as 30 percentage points in NBC News/WSJ national polls last year.
Once people started learning more about Bernie, they would more than likely be a supporter.
https://twitter.com/kendrick38/status/1233214590588248069
https://www.nbcnews.com/politics/meet-the-press/nbc-news-wsj-poll-sanders-gains-ground-biden-black-voters-n1140166