Chief among the campaigners celebrating the resignation of Claudine Gay as president of Harvard University was a man who arguably did the most to push Gay, Harvard’s first Black president, out the door: Bill Ackman, a billionaire hedge-fund manager and Harvard alumnus.

Ackman, who accused Gay of antisemitism and plagiarism, was a major player in what increasingly became a rightwing campaign against the Harvard president – who said many of the attacks against her were “fueled by racial animus”.

In the past month alone, the 57-year-old has tweeted about Gay, Harvard, or both, more than 100 times to his 1 million followers. On Tuesday, he topped that with a rambling 4,000-word X post about “racism against white people”; universities’ efforts to increase diversity; and accusations that student groups were “supporting terrorism”.

Ackman’s campaign came after “years of resentment”, the New York Times reported, in part because his donations to Harvard did not give him greater influence over the university.

A previous donor to the Democratic party, Ackman has denied he has rightwing politics. But his campaign has been seized upon by conservatives and a Republican party that have long been resentful of an alleged liberal bias, and of affirmative action efforts, on college campuses and elsewhere – something commenters pointed out after Gay’s resignation.

Al Sharpton, the civil rights leader and founder of the National Action Network, was among those who blamed Ackman for Gay’s departure, citing the financier’s “relentless campaign against President Gay, not because of her leadership or credentials but because he felt she was a DEI hire”.

“President Gay’s resignation is about more than a person or a single incident. This is an attack on every Black woman in this country who’s put a crack in the glass ceiling,” Sharpton said in a statement.

The National Action Network was planning to picket outside Ackman’s office in Manhattan, Sharpton said.

“If he [Ackman] doesn’t think Black Americans belong in the C-suite, the Ivy League, or any other hallowed halls, we’ll make ourselves at home outside his office,” Sharpton wrote.

Gregg Gonsalves, an epidemiologist at Yale University, wrote on X: “Bill Ackman is a pernicious influence on American education. He thinks his money equals wisdom, and even if it doesn’t, he thinks it gives him the right to bully at will. Time to stand up to people like him. He’s odious.”

Gay’s departure came after an appearance before Congress in December, during which Elise Stefanik, a Republican congresswoman, quizzed Gay and the presidents of MIT and the University of Pennsylvania about alleged antisemitism on their campuses.

The three presidents answered questions regarding allegations of on-campus antisemitism related to the Israel-Gaza war when asked by Stefanik whether calls by students for the genocide of Jews would constitute harassment under the schools’ codes of conduct. Footage of the hearing quickly went viral.

The clips largely omitted the context that Stefanik had previously conflated “intifada”, which in Arabic means uprising, with genocide, but the hearing increased the pressure on Gay and her colleagues. The president of UPenn, Elizabeth Magill, resigned four days later.

Stefanik would seem an unlikely hero in the movement against alleged antisemitism: in 2022, she refused to rescind her endorsement of fellow New York Republican Carl Paladino after it emerged he had told a radio interviewer that Adolf Hitler was “the kind of leader we need today”.

Stefanik has also been criticized for dabbling with the idea of “great replacement theory”, a racist conspiracy theory that alleges politicians are attempting to replace white Americans with non-white immigrants, something Mehdi Hasan, an MSNBC host, alluded to when he addressed Ackman’s conduct.

“This is what happens when liberal universities roll over for rightwing, bad-faith bullies. It’s what happens when anyone anywhere rolls over to try and appease a bully. They don’t get appeased. They just come back for more,” Hasan wrote on X in response to Ackman’s missives.

Ackman responded that he was “not rightwing”, and reiterated the claim that there had been calls for genocide against Jews on campuses.

Hasan replied: “Nobody was calling for the genocide of the Jews. You’re echoing Stefanik’s lies and stunts, which is another reminder of why you’re on the right, like she is. Have you ever criticized Stefanik’s open antisemitism (great replacement, support for Trump, etc) btw? If not, why not?”

In her resignation letter, Gay said it had been “frightening to be subjected to personal attacks and threats fueled by racial animus”, but it seems Ackman may not be ready to leave the academic alone.

After it was reported that Gay would remain on the faculty staff following her resignation, Ackman tweeted: “This makes no sense. How can she continue as a member of the faculty?”

Despite Ackman’s claim that his campaign against Gay was not politically motivated, a glimpse into who had been attracted to his crusade could be seen in those who praised Ackman’s screed.

Amid a slew of supportive tweets from rightwing accounts was the Virginia Project, a Republican organization which runs a “program on un-American activities” targeting “critical race theory”, “queer theory” and “equity”; a Republican activist and close friend of George Santos; and Monica Crowley, a former Fox News contributor and Trump administration staffer who was previously found by CNN to have plagiarized multiple sources in a book she wrote in 2012.