Kamala Harris endorsed Joseph R. Biden Jr. for the Democratic nomination for president on Sunday.
Ms. Harris, who ended her own presidential campaign in December, is the latest in a parade of prominent Democrats to throw her support behind Mr. Biden, whose blowout victory in the South Carolina primary and success on Super Tuesday established him as the clear moderate alternative to Bernie Sanders.
“I have decided that I am with great enthusiasm going to endorse Joe Biden for president of the United States,” Ms. Harris said in a video posted to Twitter. “I believe in Joe. I really believe in him, and I have known him for a long time.”
In a tweet, Mr. Biden expressed gratitude and invoked his late son, Beau Biden, who served as Delaware’s attorney general when Ms. Harris held that post in California: “Kamala — You’ve spent your whole career fighting for folks who’ve been written off and left behind — and no small part of that alongside Beau. From our family: thank you.”
For Ms. Harris, though, the decision is particularly striking, because one of the biggest moments of her campaign was a forceful debate-stage exchange with Mr. Biden.
“It was hurtful to hear you talk about the reputations of two United States senators who built their reputations and career on the segregation of race in this country,” she said in June during the first Democratic debate.
“And it was not only that, but you also worked with them to oppose busing. And, you know, there was a little girl in California who was part of the second class to integrate her public schools, and she was bused to school every day. And that little girl was me.”