Newsweek has apologized for an op-ed that questioned Sen. Kamala Harris’ U.S. citizenship and her eligibility to be Joe Biden’s running mate, a false and racist conspiracy theory which President Donald Trump has not dismissed.

“This op-ed is being used by some as a tool to perpetuate racism and xenophobia. We apologize,” read Newsweek’s editor’s note on Friday, which replaced the magazine’s earlier detailed defense of the op-ed.

“We entirely failed to anticipate the ways in which the essay would be interpreted, distorted and weaponized,” read the apology, signed by Josh Hammer, opinion editor, and Nancy Cooper, global editor in chief. But they ended the note by saying that the op-ed would remain on the site, with their note attached.

The op-ed was written by John Eastman, a conservative attorney who argues that the U.S. Constitution doesn’t grant birthright citizenship. Eastman sowed doubt about Harris’ eligibility based on her parents’ immigration status. Harris’ mother was born in India and her father was born in Jamaica.

Newsweek earlier defended the piece, arguing that Eastman “was focusing on a long-standing, somewhat arcane legal debate” about the 14th Amendment and not trying to “ignite a racist conspiracy theory around Kamala Harris’ candidacy.”

But the theory is false. Harris, who was tapped by Joe Biden to serve as his running mate on the Democratic ticket, was born in Oakland, California, and is eligible for both the vice presidency and presidency under the constitutional requirements. The question is not even considered complex, according to constitutional lawyers.

Trump built his political career on questioning a political opponent’s legitimacy. He was a high-profile force behind the “birther movement” — the lie that questioned whether President Barack Obama, the nation’s first Black president, was eligible to serve. Only after mounting pressure during his 2016 campaign did Trump disavow the claims.

Asked about the matter at the White House on Thursday, Trump told reporters he had “heard” rumors that Harris does not meet the requirement to serve in the White House. The president said he considered the rumors “very serious.”