WASHINGTON - Joe Biden has finally announced his selection for his 2020 election running mate – Kamala Harris.The pick fulfills the Democratic presidential contender’s promise to select a woman as his running mate, and puts to rest the sometimes bristly rivalry the pair shared during the early phase of the Democratic primary.The rivalry provided one of the nomination race’s most memorable moments when Harris sharply criticized Biden for his record on racial justice, calling his positive description of a past working relationship with segregationist statesmen as “hurtful.”Harris has since dialed back the attack, reportedly telling a colleague that the exchange was “just politics.”Harris dropped out of the race for president in December 2019.