"And now I want to hand it over to the president of Ukraine, who has as much courage as he has determination, ladies and gentlemen, President Putin," Biden said, referring to Zelenskyy, before realising his error and correcting himself.

To a question about what concern he has about Vice-President Kamala Harris's ability to beat Donald Trump if she ran for the top job, Biden replied: "I wouldn't have picked Vice-President Trump to be vice-president if I didn't think she was qualified to be president".