FILE – In this Feb. 25, 2020, file photo from left, Democratic presidential candidates, Sen. Elizabeth Warren, D-Mass., Sen. Bernie Sanders, I-Vt., former Vice President Joe Biden, and Sen. Amy Klobuchar, D-Minn., participate in a Democratic presidential primary debate in Charleston, S.C. (AP Photo/Matt Rourke, File)

WASHINGTON (AP) — Elizabeth Warren endorsed Joe Biden on Wednesday, becoming the last of the former vice president’s major Democratic presidential rivals to formally back him.

The Massachusetts senator 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.

Sanders, who suspended his campaign last week, endorsed Biden on Monday, A day later, former President Barack Obama announced his public backing of Biden.

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. Today, I’m proud to endorse @JoeBiden as President of the United States. pic.twitter.com/VrfBtJvFee — Elizabeth Warren (@ewarren) April 15, 2020