Vice President Kamala Harris has debuted her presidential campaign in the swing state of Wisconsin on Tuesday.Mr Biden announced on Sunday that he was stepping aside after a disastrous debate performance catalysed fears that the 81-year-old was too frail for a second term.

Vice President Kamala Harris has debuted her presidential campaign in the swing state of Wisconsin on Tuesday.Mr Biden announced on Sunday that he was stepping aside after a disastrous debate performance catalysed fears that the 81-year-old was too frail for a second term.