WASHINGTON — Donald Trump Jr., the president’s eldest son, shared another person’s tweet with his millions of followers during the Democratic debate on Thursday that falsely claimed Senator Kamala Harris was not black enough to be discussing the plight of black Americans.
“Kamala Harris is implying she is descended from American Black Slaves,” Ali Alexander, a member of a right-wing constellation of media personalities, wrote on Twitter. “She’s not. She comes from Jamaican Slave Owners. That’s fine. She’s not an American Black. Period.”
Mr. Trump, a valuable Republican surrogate as his father faces a bruising 2020 race, posted the tweet of unverified information, then asked his more than three million followers: “Is this true? Wow.” By the end of the night, Mr. Trump had deleted his message, and by Friday, a spokesman said it had all been 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,” said the spokesman, Andy Surabian, “and once he saw that folks were misconstruing the intent of his tweet, he quickly deleted it.”
But by then, the original message, questioning the background of a presidential candidate who is of Indian and Jamaican descent, had already spread far and wide. For people like Mr. Alexander — an alt-right fringe figure who has also gone by the name Ali Akbar — the entire point of commenting was to go viral and counteract any progress made by a Democrat like Ms. Harris. She caught Joseph R. Biden Jr., the presumed front-runner, off guard on Thursday night by questioning his track record on race.
Because his tweet was elevated by valuable surrogates like the president’s son, Mr. Alexander has become part of a loose network of accounts weaponized by the Trump campaign as part of its effort to discredit candidates.
The facts are these: Ms. Harris, a first-term senator from California and a former prosecutor, is the biracial daughter of a Jamaican father and Indian mother. She has faced repeated questions about her race throughout her career, but has at times resisted being put into one category or another. In an interview with The Washington Post this year, Ms. Harris called herself “an American,” defying calls at various points for her to choose.
“My point was: I am who I am,” Ms. Harris said at the time. “I’m good with it. You might need to figure it out, but I’m fine with it.”
On Thursday evening, Ms. Harris was more forceful in relaying her experiences with racism. “Growing up, my sister and I had to deal with the neighbor who told us her parents couldn’t play with us because she — because we were black,” Ms. Harris said.
She was also forceful in her criticism of Mr. Biden, who served as vice president to the nation’s first black president but who drew intense scrutiny a week ago for expressing a willingness to work with lawmakers who have different views — a group that at one point included segregationist senators.
Ms. Harris told Mr. Biden during the debate that it was “hurtful” that he’d worked with segregationists. She also accused him of working with them to oppose busing students to schools to better integrate them, a claim Mr. Biden denied.
“And, you know,” Ms. Harris said, “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.”
Her impassioned embrace of her personal history was what Mr. Alexander and then Mr. Trump pounced on. By the end of the evening, even though Mr. Trump had deleted his tweet, a round of accounts began sharing the contents of Mr. Alexander’s tweet questioning Ms. Harris’s background.
This activity caught the attention of Caroline Orr, a Virginia-based researcher who studies disinformation and elections. Mr. Alexander is a real person, but Ms. Orr hinted that the activity may have been the work of Twitter bots meant to spread his misinformation.
“A lot of suspect accounts are pushing the ‘Kamala Harris is not Black’ narrative tonight,” Ms. Orr wrote on Twitter. “It’s everywhere and it has all the signs of being a coordinated/artificial operation.”
On Friday, Mr. Alexander denied that his tweet had been part of an organized effort to spread that message at all, and he has characterized as racist inquiries into what he meant by his original tweet.
Lily Adams, an aide to Ms. Harris, on Friday criticized Mr. Trump’s tweet. “This is the same type of racist attack his father used to attack Barack Obama,” she said. “It didn’t work then and it won’t work now.”
Mr. Trump, for his part, had moved on: He sent a fund-raising text message to followers of the Trump campaign.