Elizabeth Warren endorses Joe Biden for president

 Sen. Elizabeth Warren endorsed Joe Biden for president on Wednesday morning.

The Massachusetts Democrat made the announcement on Twitter, becoming the last of the former vice president’s major rivals to formally back him in the 2020 race.

“In this moment of crisis, it’s more important than ever that the next president restores Americans’ faith in good, effective government—and I’ve seen Joe Biden help our nation rebuild,” Warren said. “Today, I’m proud to endorse @JoeBiden as President of the United States.”

Warren dropped out of the race last month, shortly after a disappointing third-place finish in her home state. She refused to immediately endorse Biden or her fellow progressive Bernie Sanders.

9b917524-US-VOTE-2020-DEMOCRATS-DEBATE-POLITICS

Massachusetts Senator Elizabeth Warren (R) and Former Vice President Joe Biden shake hands as they arrive onstage for the third Democratic primary debate of the 2020 presidential campaign season hosted by ABC News in partnership with Univision at Tex

Former President Barack Obama and Sanders previously endorsed Biden earlier this week.

RELATED: Obama endorses Biden, says former VP has 'qualities we need'

This story was reported from Cincinnati. The Associated Press contributed.