Scott Pruitt, the embattled administrator of the Environmental Protection Agency, has resigned after months of controversy surrounding his spending and ethics. 

President Donald Trump announced the personnel change on Twitter, saying he will "always be thankful to [Pruitt]" for his service. The EPA's deputy administrator Andrew Wheeler, who the Senate confirmed in April, will assume the role of acting administrator on Monday. Wheeler is a former coal lobbyist. 

Pruitt, 50, was under scrutiny for questionable business practices, including enlisting aides to obtain special favors for him and his family, such as searching for a used Trump International Hotel mattress, lotion from the Ritz-Carlton hotel, and even reaching out to Chick-fil-A's CEO in the hope of helping his wife win a franchise of the restaurant. His unusual spending habits, including his purchase of a $43,000 telephone booth, also caught the eye of a government watchdog agency, and ultimately ruled that purchase as illegal because the EPA did not notify Congress that it would exceed a $5,00 cap on furnishing officials' offices. Pruitt is the subject of more than a dozen federal investigations. 

Pruitt, who was a former Oklahoma attorney general who was known for filing lawsuits against the EPA, was the agency's 14th administrator of the EPA, and the shortest-serving. During his tenure, he was praised by conservatives for his de-regulation measures. He was also a key figure in urging the president to withdraw the United States from the Paris climate agreement. 

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In his resignation letter to the president, Pruitt said the "unrelenting attacks" on him and his family have taken a "sizable toll," but thanked Trump for the honor of serving him.