Mr. Pruitt, a former Oklahoma attorney general, had been hailed by conservatives for his zealous deregulation, but could not overcome the stain of ethics questions.
WASHINGTON — President Trump accepted the resignation of Scott Pruitt, the Environmental Protection Agency administrator, he said in a tweet on Thursday.
Mr. Pruitt had been hailed as a hero among conservatives for his zealous deregulation, but he could not overcome the stain of numerous ethics questions about his alleged spending abuses, first-class travel and cozy relationships with lobbyists.
Mr. Pruitt also came under fire for enlisting aides to obtain special favors for him and his family, such as reaching out to the chief executive of Chick-fil-A, Dan T. Cathy, with the intent of helping Mr. Pruitt’s wife, Marlyn, open franchise of the restaurant.
Mr. Pruitt, a former Oklahoma attorney general who built his career on lawsuits against the agency he would eventually lead, remained a favorite of Mr. Trump’s for the majority of his tenure at the E.P.A. He began the largest regulatory rollback in the agency’s history, undoing, delaying or blocking several Obama-era environmental rules. Among them was a suite of historic regulations aimed at mitigating global warming pollution from the United States’ vehicles and power plants.
Mr. Pruitt also played a lead role in urging Mr. Trump to follow through on his campaign pledge to withdraw the United States from the 2015 Paris climate agreement, despite warnings from some of the president’s other senior advisers that the move could damage the United States’ credibility in foreign policy. Under the landmark accord, nearly every country had committed to reducing emissions of planet-warming fossil fuel pollution.
The E.P.A.’s deputy administrator, Andrew Wheeler, a former coal lobbyist who shares Mr. Pruitt’s zeal to dismantle climate change regulations, will act as the agency’s leader until a new administrator is nominated by Mr. Trump and confirmed by the Senate.
In 2017, Mr. Pruitt made headlines for questioning the established science of human-caused climate change, contradicting decades of research by scientific institutions, including his own agency. Although Mr. Pruitt was harshly criticized for the remarks, they did not affect his good standing with a president who has also mocked climate science.
Mr. Trump has repeatedly told associates that Mr. Pruitt has done what he has wanted in terms of cutting regulations, so he has been reluctant to let him go. Mr. Pruitt has made himself available to the president as a confidante as well as a possible next attorney general.