(CNN) Andrew Wheeler, the new acting head of the Environmental Protection Agency, should do everything he can "to restore the American people's confidence in the agency's mission, which is the protection of human health and our environment," Delaware Sen. Tom Carper, the top Democrat on the Environment and Public Works Committee, wrote in a letter to Wheeler on Friday.
Carper, a vocal critic of Wheeler's predecessor Scott Pruitt, wrote according to a copy shared with CNN that Wheeler has been "granted an enormous challenge and responsibility, but an even greater opportunity."
"The damage Scott Pruitt has done to the Agency will not easily be undone," he wrote. "While you and I have not always agreed, and will not always agree, on every environmental policy matter, it is my hope and expectation that you will carefully consider the lessons of the past as you prepare to chart the Agency's future."
In the letter, Carper also recommended a series of actions he believes Wheeler should take to "restore confidence" in the agency after Pruitt's tenure. They include responding to congressional oversight letters in a complete, accurate, and timely manner; implementing the Toxic Substances Control Act and withdrawing a proposal to repeal emissions standards for glider trucks.
President Donald Trump tweeted on Thursday that he had accepted Pruitt's resignation, and that Wheeler would take over the agency on Monday. Wheeler was confirmed as EPA's deputy administrator in April.
Pruitt's resignation came a week after several of his top aides spoke to the House Oversight Committee, which has been investigating Pruitt, and revealed new details of some of the ethical scandals that mired his time at EPA.
At the time of his resignation, there were more than a dozen inquiries related to Pruitt's conduct by the EPA's Office of Inspector General, the House Oversight Committee, the Government Accountability Office and other watchdogs.
On Thursday, Trump tweeted praise of Wheeler, saying that he has "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!"
If Trump nominates Wheeler to lead the agency in a permanent capacity, a Senate vote would be required.