However, only 78 of 950 such organizations are participating in the government program, according to a Treasury spokesman. The rest do not have authorization to participate because they have not previously been approved by the Small Business Administration to make loans backed by the agency. Their representatives say they do not yet have clarity from the government on how to get that approval quickly enough to participate in the emergency program.

On Monday, the leaders of the Opportunity Finance Network, a group that represents the community development organizations, met with Treasury officials to suggest ways that the government could quickly approve the lenders for the program. But later, in a statement posted on its website, the group said that Treasury officials were “noncommittal” about what, if any, actions they would take in response to the group’s recommendations. A Treasury spokesman did not provide a timeline for when more community organizations might be approved to participate.

In their letter, the group of black investors, including Ariel’s co-chief executive Mellody Hobson, who serves on the board of JPMorgan Chase, proposed that a quarter of the $250 billion in additional money for small businesses that Congress is considering adding to the program be set aside for black businesses.

“This roughly $68 billion will only begin to address the disparities within capitalism brought into relief by coronavirus,” they wrote. “By prioritizing clients that already have existing lines of credit, black businesses and nonprofits find themselves yet again excluded from live-saving relief.”

Some federal lawmakers have proposed that part of the second stimulus could be directed to local business development organizations that focus specifically on helping minority businesses so that they can hire lawyers and offer advice to minority-owned businesses about how to get help during the pandemic. The $2 trillion CARES Act allotted $10 million for minority chambers, but some lawmakers say that is far from enough.

During a call on Wednesday with Vice President Mike Pence, members of the Congressional Black Caucus expressed concern that funds from the program were not reaching black business owners, according to Representative Emanuel Cleaver II, Democrat of Missouri and a caucus member who was briefed on the call after it took place. Mr. Pence said that the program had gotten off to a shaky start in general, Mr. Cleaver said.

“He did admit that they had had some difficulty,” Mr. Cleaver said. “The fear now is that if we don’t act quickly, by the time we get the help for minority businesses by way of having advisers through minority chambers, the fear is the money will be exhausted.”