Speculation grows that senior figures including Barack Obama could step in and ask president to throw in the towel

What can we say to make you go, Joe? It is the question that more and more Democrats – elected members and ordinary voters – are asking as the rumbling crisis over Joe Biden’s presidential candidacy, sparked by a pitiful display in the debate in Atlanta, degenerates into a war of attrition.

Last Thursday, the president’s fate appeared perched on the edge of an abyss, as Congress members deserted him, senators poured out their heartfelt fears at a tearful meeting with White House staff, and even his own close aides and advisers briefed reporters that he should stand aside.