Donald Trump retweeted a charge from two campaign surrogates that Hillary Clinton had a Ku Klux Klan member as “her mentor.”

The Saturday tweet came at the end of a week in which Clinton criticized Trump’s ties to the so-called “alt-right” movement and released an ad featuring Klan members discussing their support of Trump.

The tweet came from Diamond and Silk—sisters Lynette Hardaway and Rochelle Richardson, who are black—who vocally support Trump and speak frequently at his rallies.

It references remarks Clinton made about former West Virginia Sen. Robert Byrd, after his death in 2010, Clinton called Byrd “a true American original, my friend and mentor.”

Byrd, the longest-serving U.S. senator in history, served as a grand dragon in the Klan in his youth, which he described as “an extraordinarily foolish mistake” in a 2005 memoir. When he died, the NAACP issued a statement saying his career “reflects the transformative power of this nation” as he “went from being an active member of the KKK to a being a stalwart supporter of the Civil Rights Act.”

In an appearance on CNN’s State of the Union, Trump’s running mate, Mike Pence, said that the campaign does not welcome the support of former Klan wizard David Duke.

“It does really bother me,” he said. “And Donald Trump made it clear repeatedly in this week that not only does he denounce David Duke, but we don’t want the support of people who think like David Duke.”

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Write to Mahita Gajanan at mahita.gajanan@time.com.