Biden announces 2020 White House bid

Former US vice-president Joe Biden, vowing to fight for the "soul of this nation", announced on Thursday that he would seek the Democratic Party's presidential nomination, and then attended a private event in Philadelphia to raise money for the long campaign ahead.

Biden, 76, made his announcement in a three-and-a-half minute video posted on Twitter.

"If we give (US President) Donald Trump eight years in the White House, he will forever and fundamentally alter the character of this nation, who we are, and I cannot stand by and watch that happen," Biden said in the video.