Joe Biden has withdrawn from the US presidential race, saying it is in the best interest of his party and country. He has now endorsed his vice-president Kamala Harris to be the Democratic candidate - as have a growing number of senior members of the party.  On the Sky News Daily, Niall Paterson talks to US Correspondent Martha Kelner about the timing of Biden's departure and to Scarlett Maguire from JL Partners about what the polls are saying.  Producer: Emma Rae Woodhouse Editor: Philly Beaumont