Donald Trump has maintained his support for Environmental Protection Agency head Scott Pruitt, who is facing multiple claims of ethical infractions and spending irregularities.

Chief of Staff John Kelly told Trump this week that Pruitt needed to go for the sake of the Administration, according to “two officials briefed about the conversation”. However, Trump held firm — reportedly because he sees Pruitt as a possible replacement for Attorney General Jeff Sessions amid the ongoing Trump-Russia investigation.

Trump lashed out on Twitter on Friday:

In his year at the EPA, Pruitt — who pursued numerous cases against the Agency as Oklahoma Attorney General — has turned the agency from a protector of the environment into one gutting regulations, halting enforcement, and suspending scientific findings on issues such as climate change. The EPA has avoided a cut of more than 30% in funding because of the failure of the Trump Administration to pass a budget, but staff are still being reduced and morale is low.

However, all this has only endeared Pruitt to Trump, who favors any regulatory rollback, according to sources within the Administration. White House Press Secretary Sarah Huckabee Sanders said on Friday, “No one other than the president has the authority to hire and fire. The President feels that the administrator has done a good job at EPA,” adding that a White House internal investigation is “continuing to review any of the concerns that we have”.

The House Oversight Committee is investigating Pruitt’s expenditure of more than $100,000 on first-class flights, and has begun an inquiry into revelations that the EPA head rented a Washington condominium, co-owned by the wife of an energy lobbyist ,for $50 per night.

Whistle-blowing EPA officials say Pruitt’s expenditure on security and travel is almost $3 million, with a 20-member full-time detail — more than three times the size of his predecessor’s part-time contingent — often claiming overtime.

Pruitt has reportedly sidelined or demoted at least five high-ranking EPA employees who raised questions about his spending.

Privately, many senior White House aides are furious with Pruitt over the ethical issues, according to sources.

But Trump — who has recently purged advisors such as Secretary of State Rex Tillerson, National Security Advisor H.R. McMaster, and Veterans Administration head David Shulkin — told reporters on Thursday, “I think [Pruitt] has done a fantastic job at EPA. I think he’ll be fine.”