Following an 18-month tenure filled with a cascade of scandals, EPA Administrator Scott Pruitt resigned Thursday. 

President Donald Trump acknowledged Pruitt's resignation in a tweet and announced that EPA Deputy Administrator Andrew Wheeler will run the agency in the interim, starting Monday.

Pruitt was known most for his denial of climate change, his efforts to repeal tightening emissions standards that led to increasing fuel economy standards, for threats to roll back California's right to set tighter emissions (and resulting higher fuel economy) standards, and his rollback of the Clean Power Plan, which required coal-powered electricity plants to implement carbon capture technology or convert to cleaner fuels.

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Those regulations had been credited with significant potential gains in air quality as well as reductions in demand for petroleum.

(Pruitt also limited the scope of the Clean Water Act, allowing more pipelines and oil trains through sensitive areas.)

Trump praised Pruitt in a tweet for having "done an outstanding job."

EPA Acting Administrator Andrew Wheeler

EPA Acting Administrator Andrew Wheeler

Wheeler, a lawyer with degrees in biology and business administration, started his career at the EPA working on pollution prevention, toxic chemical, and right-to-know issues in the Clinton and first Bush administrations. He has also worked on nuclear safety, clean energy, and clean water standards as a congressional staffer.

Following his stint in government, he worked as counsel to coal producer Murray Energy, and lobbied against climate change policy and greenhouse gas emission regulation. He is known as a coal supporter and has been vice president of the Washington Coal Club.

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In 2010, he said it was his impression that the United Nations Intergovernmental Panel on Climate Change developed policies based more on a political worldview than on scientific facts, according to The New Republic.

Pruitt, the former Attorney General of Oklahoma who won fame for repeatedly filing lawsuits against the EPA, lost the faith of Trump after generating a litany of scandals in Washington.

He was investigated for renting a room from the wife of an oil industry lobbyist for a discounted rate (which he only had to pay when he stayed there), for traveling first-class and installing a $43,000 sound-proof booth at the EPA headquarters at taxpayer expense, for using EPA criminal investigators as his private security staff, and for tasking subordinates with booking his travel and finding a six-figure job with a lobbying firm in Washington for his wife.

Even some congressional Republicans had suggested he should resign.

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