Former White House hopeful Elizabeth Warren on Wednesday endorsed her onetime rival Joe Biden, becoming the final major Democratic candidate to publicly support his presidential bid.

The formal backing from Warren, a progressive senator from Massachusetts, comes two days after ex-candidate Bernie Sanders announced his backing for Biden, and 24 hours after Barack Obama formally endorsed his two-term vice president.

"We can't afford to let Donald Trump continue to endanger the lives and livelihoods of every American," Warren said in a video message, referring to the Republican incumbent. "And that's why I'm proud to endorse Joe Biden as president of the United States."