Samantha Dravis (above, center), the senior counsel and associate administrator of the EPA’s office of policy, submitted her resignation last week, Politico and several other outlets reported Thursday.

CNN characterized Dravis as a top aide to EPA Administrator Scott Pruitt and reported that she was responsible for executing much of Pruitt’s deregulatory agenda over the past year. The Washington Post noted that her resignation comes as Pruitt relies on an ever-smaller group of advisers to make decisions.

“It has been an honor to serve in this role at EPA, and I am enormously grateful for the opportunity,” Dravis told CNN. “I wish Administrator Pruitt and all of the public servants at EPA the very best.”

Dravis had previously worked in George W. Bush’s White House as associate director of political affairs, according to her EPA bio, and then became president of the Rule of Law Defense Fund.

Pruitt himself resigned as chairman of that organization, an advocacy group tied to the Republican Attorneys General Association, before joining the Trump administration.

The Rule of Law Defense Fund opposes regulations the EPA put in place during the Obama administration, including the Clean Power Plan, and has received funding from the Koch brothers’ group Freedom Partners, according to a Bloomberg report. Democrats were critical of Pruitt’s leadership of the group during his confirmation process, painting him as a prime example of a Trump Cabinet nominee who’d worked to dismantle the agency he was tasked with leading.

The Post reported, citing several unnamed agency officials “with firsthand knowledge of the matter,” that Dravis’ resignation announcement last week was not connected to the numerous scandals currently afflicting her boss at EPA. A deputy White House press secretary, Hogan Gidley, said Thursday that he “can’t speak to the future of Scott Pruitt.”