A senior White House official resigned Wednesday after learning that his past marijuana use would keep him from receiving a security clearance, according to a Politico report.

The departure of George David Banks, who advised the White House on energy and environment as a member of the National Economic Council, comes amid growing criticism of a slew of senior officials working in the Trump administration without permanent security clearance.

Banks told Politico that the White House Counsel’s office said Tuesday that he would not receive permanent clearance because he had admitted to smoking pot in 2013. The White House subsequently accepted his offer of resignation, he said.

“It was an honor to serve the president at the White House and I look forward to supporting the president in the future,” he told Politico.

White House Staff Secretary Rob Porter resigned last Wednesday following public allegations that he abused multiple ex-wives. David Sorensen, a White House speechwriter, resigned on Friday over domestic abuse allegations. As many as 40 White House officials are said to be working without full security clearance, including Jared Kushner, President Trump’s son and law and key advisor, according to a CNN report.

Banks, a former aide in the George W. Bush administration, advised the Trump White House on international energy, environment and climate issues. He often served as the administration’s public face on international climate change issues, including at international climate change negotiations.

White House officials in at least the previous administration have admitted to smoking marijuana, including President Obama and his National Security Advisor Susan Rice. The Trump administration has shifted gears on marijuana, making enforcement of the federal restrictions on the drug a priority.

The White House did not respond to a request for comment. An email to Banks’s White House email address was returned as undeliverable early Wednesday afternoon.

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Write to Justin Worland at justin.worland@time.com.