On Thursday, President Trump tweeted that Environmental Protection Agency (EPA) Administrator Scott Pruitt had submitted his resignation.

Pruitt had been considered among the most loyal of Trump's appointees, but the former Oklahoma Attorney General made headlines over the past several months with repeated scandals over extravagant spending. Pruitt reportedly used agency funds to buy hundreds of thousands of dollars worth of tactical pants and other security-related items. He also used agency resources to help his wife find a job and even to help him purchase a used Trump hotel mattress. Questions about who Pruitt promoted and how raises were doled out also caused significant damage to Pruitt's public image. Thirteen different federal investigations had been opened up into the administrator's conduct.

Trump's tweet mentioned none of this Thursday afternoon, however. "I have accepted the resignation of Scott Pruitt as the Administrator of the Environmental Protection Agency," the President tweeted. "Within the Agency Scott has done an outstanding job, and I will always be thankful to him for this. The Senate confirmed Deputy at EPA, Andrew Wheeler, will..."

A second tweet continued: "... on Monday assume duties as the acting Administrator of the EPA. I have no doubt that Andy will continue on with our great and lasting EPA agenda. We have made tremendous progress and the future of the EPA is very bright!"

Ars reached out to the EPA to confirm the resignation. Spokeswoman Molly Block did not give a statement but referred back to the president's tweet.

Before joining the EPA as deputy administrator, Andrew Wheeler worked as a lobbyist for Robert Murray, executive of Murray Energy Corporation, one of the largest coal companies in the US. Murray has also donated significant amounts of money to Trump and is a vociferous critic of any regulation on mining and coal industries.

Draft regulation

The news of Pruitt's resignation comes just as the EPA completed drafting a potential replacement for the Clean Power Plan according to The New York Times. The draft hasn't been made public, but it was described in detail to the Times by "industry officials who have worked closely with the agency to shape the rule."

Block confirmed to Ars that "The Agency is in the process of developing a proposal regarding the Clean Power Plan."

"That proposal would go through interagency review before administrator signature and public availability for review and comment," Block added.

The Obama-era Clean Power Plan would have required states to reduce their energy-related emissions to 32 percent below 2005 levels by 2035. The rapid closure of coal plants has seemed to put this goal within reach for most states despite Trump's move to kill the regulation last spring.

But the Clean Power Plan had already gone through the process of becoming a law, anchored by a so-called "endangerment finding" by the agency, which now requires the EPA to do something in response to climate change. The EPA considered challenging the endangerment finding so it could drop regulation of the power sector altogether. But the Times says the EPA's draft rule allows the agency to avoid protracted legal battles by regulating coal plants very lightly.

"The proposal, according to industry attorneys familiar with the plan, would recommend regulating the emissions of individual coal plants, which would call for modest upgrades, such as improving efficiency or substituting fuel," the paper wrote.

The details of the plan are expected to be sent to the president in the coming days, according to the Times.

Though replacing the Clean Power Plan with weaker regulations could be a quick way to avoid protracted legal action involving the endangerment finding, the new acting administrator's old boss Robert Murray recently wrote to the president urging him to challenge the endangerment finding.