President Donald Trump has nominated acting EPA administrator Andrew Wheeler for a permanent role in that position.
Here's what we know
On Wednesday, the White House announced that Trump had formally sent Wheeler's nomination to the Senate. Wheeler, 54, will need Senate confirmation, but that is unlikely to be a problem now that Republicans have increased the number of seats they hold to 53.
Acting Cabinet members can remain in their roles for a maximum of 210 days without being nominated for Senate approval. Wheeler took over as acting head of the EPA 188 days ago.
In November, Trump praised Wheeler for the way he was leading the EPA, declaring that Wheeler had "done a fantastic job." Trump said at the time that he planned to keep Wheeler as head of the EPA permanently.
Before his current role, Wheeler was confirmed by the Senate in April to be deputy EPA administrator. He was also a special assistant in the EPA's Pollution Prevention and Toxics office during the George H. W. Bush administration.
He was also previously a lobbyist for the Murray Energy Corp, a coal mining company. This has led to criticism from environmental groups, which argue that Wheeler will use his position at the EPA to benefit coal companies.
In August, Wheeler announced that the Trump administration would be freezing Obama-era guidelines that would have require U.S. vehicles to become significantly more fuel efficient by 2025.
Wheeler took over control of the agency after former EPA administrator Scott Pruitt resigned in July. Pruitt had faced questions about his spending habits while leading the EPA, including the purchase of a $43,000 secure phone booth without congressional approval. He was also accused of using agency resources to find a $200,000 job for his wife.