After President Donald Trumpabruptly firedJohn Bolton on Tuesday morning, Charles Kupperman was selected to be the acting national security adviser. Hours later, a leading Muslim civil rights group called on Kupperman to resign over his long-standing ties to an incendiary Islamophobic think tank.

Kupperman served for nearly a decade on the board of directors of the Center for Security Policy, which repeatedly promoted the conspiracy theory that members of the Obama administration were working to install Islamic law in the United States. Frank Gaffney, CSP’s founder, has suggested that Barack Obama is secretly Muslim, claimed there is a sinister “Islamization” of America and hosted a prominent white supremacist on his radio show.

The Council on American-Islamic Relations said Tuesday that Kupperman must resign immediately.

“Kupperman’s close ties with an anti-Muslim hate group make him unfit to hold any public office, let alone such a sensitive position,” Robert McCaw, CAIR’s director of government affairs, told HuffPost. “Given that CSP has continuously propagated Islamophobic conspiracy theories, Kupperman’s promotion jeopardizes the rights, safety and security of all American Muslims and could lead to unnecessary international conflicts with Muslim nations.”

“While we welcome the resignation of John Bolton, who has a long track record of promoting anti-Muslim policies and associating with hate groups, we cannot simply replace one Islamophobe with another,” CAIR Executive Director Nihad Awad added in a statement.

Kupperman’s CSP association, which tax records show lasted from 2001 to 2010, was controversial when he joined the National Security Council in an informal role earlier this year.

Gaffney, who founded the group, has made a career out of promoting Islamophobic conspiracy theories and stoking fear that there is a widespread underground movement to implement sharia law in American institutions. He also promoted the racist birther conspiracy that Obama was born in Kenya. Gaffney repeatedly targets Muslim communities that plan to build mosques and has called for a total ban on Muslim immigrants.

Gaffney also hosts a radio show that serves as a platform for himself and other extremists. White supremacist Jared Taylor appeared on the show in 2015, during which Gaffney described Taylor’s racist propaganda website as a “wonderful online publication.” Gaffney has gained other fans in the white supremacist movement: The 2011 Norway mass murderer Anders Breivik cited him in his manifesto.

Prior to joining the Trump administration, Kupperman worked as a defense executive at Boeing and as part of Lockheed Martin’s space program. He also was part of President Ronald Reagan’s administration and a foreign policy adviser to Reagan’s campaign.

Kupperman has made a quick ascent in the Trump administration, having been hired on as deputy national security adviser in January after his predecessor was fired following an unusual dispute with Melania Trump.

A longtime ally of Bolton who shares similar worldviews, Kupperman is an outspoken critic of the Iranian nuclear deal and signed on to an open letter in 2017 supporting Bolton’s plan to back out of the agreement.

It’s unclear how long Kupperman will last as acting national security adviser, and The Wall Street Journal reported Tuesday that several other officials in the Trump administration are being considered as the permanent replacement for Bolton. Among the reported choices is U.S. Ambassador to Germany Ric Grenell, who drew widespread criticism last year for saying he wanted to “empower” Europe’s conservative movements in an interview with far-right outlet Breitbart. According to CNN, another possibility is Fred Fleitz, the president and CEO of CSP.