Days after Donald Trump Jr. shared, and then deleted, a tweet questioning Senator Kamala Harris’s race, several of her rival Democratic presidential candidates lent her their support on Saturday.
Mr. Trump, President Trump’s eldest son, on Thursday had shared a tweet from Ali Alexander, a right-wing personality, that falsely claimed Ms. Harris’s racial identity did not qualify her to speak about the anguish that black Americans face.
“Kamala Harris is implying she is descended from American Black Slaves,” Mr. Alexander wrote during the second night of the Democratic debates. “She’s not. She comes from Jamaican Slave Owners. That’s fine. She’s not an American Black. Period.”
Mr. Trump shared the message, asking his more than three million followers, “Is this true? Wow.”
By Saturday, several Democratic hopefuls had begun to publicly support Ms. Harris, of California, who is the biracial child of a Jamaican father and an Indian mother.
Senator Cory Booker of New Jersey tweeted that Ms. Harris does not have anything to prove, and Senator Bernie Sanders of Vermont wrote: “Donald Trump Jr. is a racist too. Shocker.”
Other candidates also responded to the inflammatory tweet.
“The presidential competitive field is stronger because Kamala Harris has been powerfully voicing her Black American experience,” Mayor Pete Buttigieg of South Bend, Ind., wrote on Twitter. He said that Ms. Harris’s first-generation story embodied the American dream and that it was time to end “birther-style attacks.”
Senator Amy Klobuchar of Minnesota tweeted that the attacks against Ms. Harris were “unacceptable.” “We are better than this (Russia is not) and stand united against this type of vile behavior,” Ms. Klobuchar wrote.
Former Vice President Joseph R. Biden Jr., whom Ms. Harris had challenged during the debate, said the same forces that used “birtherism” to question President Barack Obama’s American citizenship and race were now being used against Ms. Harris. “It’s disgusting and we have to call it out when we see it,” Mr. Biden wrote on Twitter. “Racism has no place in America.”
Senator Elizabeth Warren of Massachusetts, who labeled the attacks “racist and ugly,” also challenged technology companies to stop “these vile lies dead in their tracks.”
After Mr. Trump deleted the tweet he had shared, his spokesman claimed it was a misunderstanding.
“Don’s tweet was simply him asking if it was true that Kamala Harris was half-Indian because it’s not something he had ever heard before,” the spokesman, Andy Surabian, said at the time. He added that the tweet was deleted after it was recognized that followers were “misconstruing” its intent.
Ms. Harris has faced attacks on her race before, and has sometimes pushed back at attempts to label her.
In February, Ms. Harris told The Washington Post that she called herself “an American.”
“My point was: I am who I am,” she said. “I’m good with it. You might need to figure it out, but I’m fine with it.”