As Democratic leaders and voters called on President Biden to step aside after his faltering debate performance, Black women remained his firewall of support.

During conversations at a national music festival on Saturday in New Orleans, a small organizer gathering in rural Georgia immediately after the debate last month, and in recurring chats over text chains and phone calls, Black female Democrats have affirmed and reaffirmed their willingness to vote and organize their communities to back Mr. Biden and Vice President Kamala Harris, whose place on the presidential ticket they vigorously lobbied for in 2020.

Many acknowledged that the president’s debate performance was flawed. Others shared concerns that his weakened state and meandering answers on the debate stage would make it more difficult for them to energize Black voters, who have already expressed a lack of enthusiasm for the Democratic ticket.

But they have joined a broad swath of Black lawmakers in publicly dismissing the idea — circulating among others in the party, including a group of top House Democrats — that Mr. Biden should step aside.

“All the airwaves attention that Democrats are putting on this and not putting on efforts to convince and motivate voters is just completely distracting,” said Stefanie Brown James, a co-founder of the Collective PAC, an organization that supports Black candidates at all levels of government. “I just don’t think it’s helpful right now.”

Black women have long been the Democratic Party’s most reliable voting bloc. More than 91 percent of Black women who voted in 2020 supported Mr. Biden, and polls have consistently shown they are still his most stalwart constituency, one that has yet to crack even as those same surveys suggest a broader slippage of support among Black voters.