Ex-Vice President Biden launches 2020 presidential campaign

WASHINGTON — Former Vice President Joe Biden formally joined the crowded Democratic presidential contest on Thursday, betting that his working-class appeal and ties to Barack Obama's presidency will help him overcome questions about his place in today's increasingly liberal Democratic Party.He made his announcement in a video posted on Twitter.The core values of this nation… our standing in the world… our very democracy...everything that has made America -- America --is at st