The Senate is set to vote on Andrew Wheeler to be the number two official at the Environmental Protection Agency amid ethics concerns plaguing EPA chief Scott Pruitt and calls from Democrats for him to resign.
If Pruitt left, it could fall to Wheeler to run the agency until a new administrator is confirmed.
Two GOP leadership aides told CNN they expected Wheeler to be approved, which would make him the latest appointee at the agency with close ties to the energy industry.
His firm's clients include Murray Energy, which bills itself as "the largest coal mining company in America."
Senate Minority Leader Chuck Schumer, D-New York, blasted Wheeler as "a former industry lobbyist who has worked on behalf of big polluters and climate change deniers. He has spent years working to undermine or lobby against the environmental protections he may soon oversee."
Prior to his lobbying work, Wheeler served on Capitol Hill as a Republican staff member for the Senate Environment and Public Works Committee and as a top aide to Sen. Jim Inhofe, an Oklahoma Republican and an outspoken climate change skeptic who told CNN last month the EPA is "brainwashing our kids."
New Mexico Democratic Sen. Tom Udall said Wednesday that Wheeler should be carefully vetted, as if he were taking over for Pruitt now. Udall told reporters that he believes Wheeler wouldn't be a much better option to run the agency.
"The problem with the Wheeler nomination is if Trump (fires Pruitt) tomorrow, Wheeler is in fact the administrator, and that is a very, very serious problem," Udall said. "I know that there are many Republicans who haven't spoken out yet, but privately they are very disturbed by what Scott Pruitt is doing at the EPA."
While there is widespread opposition to Wheeler in the Democratic caucus, two Democrats running for reelection from energy producing states that strongly backed President Donald Trump in 2016 have said they will vote for him: Joe Manchin of West Virginia and Heidi Heitkamp of North Dakota.
"After meeting with Mr. Wheeler and reviewing his record, I've decided to support his nomination," Heitkamp said in a statement provided to CNN. "I believe he'll be open to working on issues important to North Dakota in a pragmatic and fair way, and I'll hold him accountable to make sure he implements the mission of the EPA in a way that works for my state."
One key centrist Republican has also signaled support for Wheeler.
"Mr. Wheeler has demonstrated that he understands the mission of the EPA and the role of Congress when it comes to oversight and accountability," said Maine Sen. Susan Collins in a statement.
Wheeler's nomination comes amid a steady stream of negative headlines involving Pruitt in recent weeks and months that has official Washington wondering whether the embattled agency chief can hold onto his job.
Most recently, Pruitt has been fighting stories revealing he paid about $6,100 over the course of a six-month lease last year to rent a room in a condo owned by Vicki Hart, a health care lobbyist whose husband, Steven Hart, has lobbied the EPA. His daughter also reportedly lived there while she was interning in Washington.
He paid $50 per night, according to the reports, and paid only for the nights he used the condo.
The federal government's top voice on ethics David Apol sent a letter to the agency outlining areas of concern regarding Pruitt. Apol, the acting director and general counsel of the Office of Government Ethics, summarized reports of Pruitt's conduct, including the rental agreement, as well as EPA spending on Pruitt's travel and security.
The letter also expresses concern with reports of Pruitt bypassing the White House to give raises to favored aides and other employees who faced job changes after raising concerns over his conduct.