BOCA GRANDE, Fla. (AP) — William H. Regnery II, the heir to a family publishing fortune who was known for his quiet but influential support of extreme right-wing causes in the United States has died at 80.

He died at his home in Boca Grande, Florida, on July 2. A person who answered the phone at the Lemon Bay Funeral Home and Cremation Services in Englewood, Florida, on Saturday confirmed they handled Regnery's arrangements, but would provide no additional information.

Cassie Miller, a senior research analyst for the Southern Poverty Law Center, said in an email Saturday that Regnery's material contributions helped to build networks of racist activists and a large body of pseudoscientific literature that Regnery hoped would legitimize his calls to build a white ethnostate.

“Though he usually operated in the background, Regnery was an extremely influential figure in the radical right,” Miller said.

In 2016, an Associated Press review of tax records found that the National Policy Institute, founded by Regnery, and three other groups at the forefront of the white nationalist movement had registered as charities and raised more than $7.8 million in tax-deductible donations over the previous decade.

Regnery spent much of his life using his family’s money to build the institutional infrastructure that would support the so-called alt-right — an offshoot of conservatism mixing racism, white nationalism, anti-Semitism and populism — and help to propel figures like Richard Spencer into the spotlight, Miller said.

“Regnery’s real legacy is not what he built, but the immense harm that he caused,” she said.

Spencer himself tweeted, of Regnery, on July 12, saying he “was fortunate to have known him and learned much from him.”

In a 2017 article, BuzzFeed News said Regnery felt his ideas were redeemed by the candidacy of now former President Donald Trump.

“I think Trump was a legitimatizer,” Regnery told the publication. White nationalism “went from being conversation you could hold in a bathroom, to the front parlor.”

Regnery was born on Feb. 25, 1941, in the Chicago area and grew up in the suburb of Hinsdale, Illinois, The New York Times reported. His father worked for the family textile business.

Regnery’s grandfather, William H. Regnery, was a founding member of the America First Committee, which sought to keep the United States out of World War II. His uncle Henry founded Regnery Publishing, which continues to publish books by a range of conservative voices, now as an imprint of the Salem Media Group and distributed by Simon & Schuster.

In 2001, Regnery founded the Charles Martel Society as a nonprofit group. The Southern Poverty Law Center says the organization is named in honor of the man who is credited with “saving Europe” by defeating an invading Muslim force at the Battle of Tours in 734.

The society is the publisher of The Occidental Quarterly, a journal that “unapologetically defends the cultural, ethnic, and racial interests of Western European peoples and examines contemporary political, social, and demographic trends that impact the posterity of Western Civilization,” the SPLC says.

Regnery's National Policy Institute was once led by Spencer, but “it appears to no longer be operational” Miller said.

The institute's death knell likely came earlier this year when a judge ordered the institute to pay $2.4 million in damages to an Ohio man injured at the deadly Unite the Right rally in Charlottesville, Virginia, said Miller.

The Associated Press