Washington — California Senator Kamala Harris threw her support behind former Vice President Joe Biden, endorsing her onetime rival for the Democratic presidential nomination after his series of impressive victories in South Carolina and on Super Tuesday.

Harris, who abandoned her own bid for the White House in December after failing to gain traction in a crowded field, said in a statement that Biden "reflects the decency and dignity of the American people and who can ultimately defeat Donald Trump" and has "a proven track record of getting things done."

"I truly believe our nation is at an inflection point. And the decision voters make this November will shape the country and the world our children and grandchildren will grow up in," Harris said. "I believe in Joe Biden and will do everything in my power to help elect him the next president of the United States."

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In a video on Twitter announcing the move, Harris said she is "supporting Joe because I believe that he is a man who has lived his life with great dignity."

"He is a public servant who has always worked for the best of who we are as a nation and we need that right now," she said.

Harris said she will campaign with Biden in Detroit on Monday night, the day before Michigan and five other states hold their primaries. Senator Bernie Sanders, Biden's last remaining opponent, has zeroed in on Michigan as he tries to bounce back from Super Tuesday.

.@JoeBiden has served our country with dignity and we need him now more than ever. I will do everything in my power to help elect him the next President of the United States. pic.twitter.com/DbB2fGWpaa — Kamala Harris (@KamalaHarris) March 8, 2020

Harris, one of two African Americans who were in the race for the Democratic nomination, went after Biden early in the primary process for his decades-old comments praising segregationist senators and opposing busing to enforce desegregation.

In a debate in June 2019, Harris told Biden it was "hurtful to hear you talk about the reputations of two United States senators who built their reputation and careers on the segregation of race in this country." Biden accused Harris of mischaracterizing his position and defended his record on civil rights.

After Harris dropped her bid in December, Biden told CBS News he didn't hold the attacks against her. "I'm not good at keeping hard feelings," he said.

Harris' endorsement on Sunday comes days after Biden swept the South on Super Tuesday, racking up large victories in states with large African-American populations, a key constituency in the Democratic primary. Those victories followed his overwhelming win in South Carolina, where he enjoyed the support of Congressman James Clyburn, the No. 3 Democrat in the House and highest-ranking black member of Congress.

Bo Erickson contributed reporting.