WASHINGTON (JTA) — Donald Trump Jr. retweeted an attack on Hillary Clinton by Kevin MacDonald, a psychologist notorious for his theories of Jewish manipulation and control.

The Aug. 29 tweet itself had nothing to do with Jews or the theories that have made MacDonald popular among Holocaust deniers. In it, MacDonald referred to Clinton’s interactions as secretary of state with UBS, a Swiss bank that also has contributed to the Clinton Foundation.

Trump’s father, Donald Trump, the Republican nominee for president, has sought to make an issue of allegations that Clinton inappropriately dealt with foundation donors while she was secretary of state in President Barack Obama’s first term. Clinton is the Democratic nominee.

The retweet by Trump Jr., first reported by political commentator Charles Johnson on his website, Little Green Footballs, has drawn unfavorable attention. Deborah Lipstadt, the Holocaust historian, on Wednesday linked to the Little Green Footballs entry on her Facebook page, and noted that MacDonald testified on behalf of David Irving when the Holocaust denier unsuccessfully sued Lipstadt for defamation.

“During the 12 weeks of Irving v. Penguin and Lipstadt, Irving called a number of witnesses,” she wrote. “Only one did not have to be subpoenaed but came of his own volition. Kevin MacDonald. Donald Trump Jr. is now retweeting his comments. Giving him added attention. Kevin MacDonald is an unabashed anti-Semite.”

As of Thursday, the retweet remained on Donald Trump Jr.’s timeline. MacDonald is not among the accounts the younger Trump, 38, is following.

According to the Southern Poverty Law Center, MacDonald, a psychologist, has published a number of books and papers on his theories that Jews survive by manipulating larger populations to gain disproportionate access to resources. He has become popular among Holocaust deniers, white supremacists and anti-Semites.

In writing for the Occidental Observer, a web site devoted to “White Identity, Interests, and Culture,” MacDonald devotes dozens of columns to the subject of “Jewish influence.” In a recent article about Trump’s weak support among Jewish voters, MacDonald wrote, “Quite simply, Jews have far more power in the media than any other identifiable group.” In another article on immigration, he accuses Jews of using “the holocaust [sic] as moral cudgel to promote Jewish interests in immigration and refugee policy.”

The Trump campaign has yet to respond to a request for comment from JTA. It is not Trump Jr.s first controversy regarding associations with the far right. In July, journalists noticed that he retweeted a white supremacist; he removed the tweet. In March, he made headlines when he gave an interview to a white supremacist radio host; Trump Jr. later said he was unaware of the radio host’s background.

Donald Trump, the nominee, also has taken flak for retweeting — that is, forwarding with apparent approval — messages from white supremacists and, in one case, an image, apparently generated by anti-Semites, of Clinton, a pile of cash and a Star of David. He has been criticized for not forcefully repudiating white supremacists who support him, although in recent weeks, his rebukes to right-wing extremists have been more robust and timely.