Today, as Mr. Biden makes his third bid for the presidency, his campaign manager is white. His chief strategist is white. His three chiefs of staff as vice president (all still key advisers) and four of the five people who have been deputy campaign managers are white, as are the leaders of his economic team…

But the fear, even among allies, is that a lack of diverse viewpoints in Mr. Biden’s brain trust could come with a long-term cost: a misinterpretation that boiling anger at Mr. Trump among black and Latino voters equates to excitement for Mr. Biden; insufficient outreach to minority groups; and — perhaps most worrisome of all — the possibility that Mr. Biden’s team would take for granted that his strength with black voters in the primaries would repeat itself in November, a complaint lodged against Hillary Clinton four years ago.

“It matters who is doing the shaping of the campaign,” said LaTosha Brown, a co-founder of the Black Voters Matter Fund. She was one of a dozen black female leaders invited to a recent private call with Mr. Biden, during which she said representation came up. “We can’t keep going and asking black folks to show up and make sure the boogeyman doesn’t get you. If you think the fear of Trump is going to be enough to move black votes, that is going to be a critical error.”