Former Vice President Joe Biden announced Thursday that he will seek the Democratic presidential nomination in 2020, shaking up the wide-open race to defeat President Trump.

“I believe history will look back on four years of this president and all he embraces as an abhorrent moment in time,” Biden said in a video announcing his White House bid.

“But if we give 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.”

His announcement offered a preview of the core message of his campaign: that Trump’s presidency has left the country in a state of crisis that only an experienced leader like himself can quell.