WASHINGTON (AP) — A top Environment Protection Agency official who helped lead the Trump administration's rollback of Obama-era restrictions of carbon emissions is resigning amid a congressional probe into whether he improperly aided former industry clients.

EPA Assistant Administrator Bill Wehrum is expected to depart at the end of June. EPA Administrator Andrew Wheeler announced Wehrum's resignation on Wednesday, thanking him for his service and friendship.

Ethics questions have dogged Wehrum since his 2017 nomination by President Donald Trump. He long represented the fossil fuels and chemical industries as a Washington lawyer. Narrowly confirmed by the Senate, Wehrum has helped lead EPA's rollbacks of clean air and carbon emissions regulations that were opposed by his former private-sector clients.

The Democratic-controlled House Energy and Commerce Committee opened an investigation in April following media reports questioning Wehrum's compliance with ethics rules barring political appointees from acting on issues involving their former employers for at least two years.

Documents obtained through a public records request by the Sierra Club showed Wehrum met with former clients and industry lawyers from his former firm without disclosing the contacts on his official calendar. He also gave a closed-door presentation last year to the Cooler Heads Coalition, a conservative pro-business group that seeks to raise doubts about mainstream climate science.

Committee Chairman Frank Pallone Jr. vowed to continue the investigations into Wehrum's conduct.

"William Wehrum's departure comes as welcome news for all those who value EPA's mission of protecting public health and the environment," said Pallone, a New Jersey Democrat. "While all of his proposed rules are dangerous, it's unlikely that any of them will survive judicial review. EPA should use this opportunity to hit reset on its agenda and refocus on protecting the health and environment of the American people."

Environmental groups cheered news of Wehrum's resignation.

"Wehrum did more damage to the Clean Air Act than any other person in the last 40 years," said Brett Hartl, government affairs director at the Center for Biological Diversity. "His legacy will be more premature deaths, more hospital visits and more asthma attacks to our most vulnerable citizens."

Anne Idsal, EPA's principal deputy assistant administrator, is to assume Wehrum's responsibilities pending the nomination of a permanent successor.

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