The White House has pushed back on questions about Joe Biden’s mental fitness, with the US president daring doubters in the party to either challenge him or unite behind his candidacy.
Mr Biden, 81, took the highly unusual step of calling in to a cable news show, saying: he is not going anywhere.
In a tense news conference later, the president’s spokeswoman rejected suggestions that he might be suffering from an undisclosed illness.
Questions about his mental acuity have intensified since a poor debate performance against Donald Trump on 27 June.
The scrutiny is unlikely to fade this week as he hosts a summit in Washington for leaders of Nato countries.
In Monday afternoon’s daily press conference, White House press secretary Karine Jean-Pierre rejected speculation that Mr Biden was being treated for Parkinson’s disease, which can cause stiff movement and slurred speech.
