US vice-president, Joe Biden, has said he is overwhelmed by his son’s death and unconvinced he could commit to being president, in an emotional interview that cast a deep pall over his deliberations about the 2016 presidential race.

Politicians, military leaders and celebrities from across the US have paid farewell to former Delaware attorney general Beau Biden, whose death at age 46 opened yet another chapter of grief for his father, vice president Joe Biden.