In the nearly three weeks since President Biden took the debate stage in Atlanta and plunged his re-election campaign into chaos, his closest consultations have been not with his White House chief of staff, his top communications strategist or even with the leader of his campaign.

Instead, he is relying on members of his family — a tight-knit clan that includes his son, Hunter, and the first lady, Jill Biden — along with a tiny group of loyalists to steer him through a self-created crisis and quell a rising rebellion against his candidacy from within his own party.

Mr. Biden has not consulted directly with the pollsters on his 500-person campaign team about the state of the race against Donald J. Trump, but has instead relied on Mike Donilon, a longtime friend, former pollster and Biden-campaign messaging guru, to summarize the numbers, with regular memos and numerous daily phone calls.

The ever-buzzing phone of Steve Ricchetti, a close counselor to Mr. Biden since his vice presidency, is the main conduit between concerned lawmakers and the president.

Mr. Biden speaks frequently to his son, Hunter Biden, who calls and texts the president and first lady multiple times a day to see how they are coping with the onslaught of scrutiny surrounding his father’s health, mental fitness and final presidential campaign.