A high-ranking political staffer at the Environmental Protection Agency has told lawmakers he faced retaliation after pushing back against outsized spending demands from Administrator Scott Pruitt for first-class flights, luxury hotels and unusual security precautions.

House and Senate Democrats sent letters Thursday to President Donald Trump and Pruitt describing a meeting the lawmakers had with Kevin Chmielewski, who was recently placed on involuntary, unpaid leave from his positon as EPA's deputy chief of staff for operations.

Chmielewski served as a key staffer for the Trump campaign before being hired at EPA last year to help oversee the agency's budget and expenditures. He said he was forced out after questioning Pruitt's spending, including ballooning costs from the administrator's full-time 20-member full-time security detail.

Trump has thus far stood by his embattled EPA chief, suggesting that Democrats and environmentalists will do anything to stop Pruitt's rollbacks of Obama-era regulations.

But in Chmielewski, Pruitt is facing criticism from a long-time Republican political operative who is known personally by both Trump and Vice-President Mike Pence. Chmielewski said he still considers himself loyal to Trump, but felt he needed to become a whistleblower because "right is right, and wrong is wrong."

Directly contradicting Pruitt, Chmielewski said the administrator personally pushed through massive raises for two close aides Pruitt had brought with him from Oklahoma, where he previously served as state attorney general. Pruitt insisted in a recent television interview that he didn't know about the raises until after they were disclosed in media reports.

EPA spokesman Jahan Wilcox said Pruitt will respond to members of Congress "through the proper channel." He did not respond to questions about Pruitt's contention that he did not know about the raises.

The letters sent Thursday were signed by five Democrats with oversight authority over EPA: Sen. Tom Carper of Delaware, Sen. Sheldon Whitehouse of Rhode Island, Rep. Elijah Cummings of Maryland, and Reps. Gerald Connolly and Donald Beyer of Virginia.

In a separate letter, Carper and Democratic Sen. Jeff Merkley of Oregon said they had learned that Pruitt had used at least four government email addresses at EPA, and that his staff had not been searching all of them in response to public records requests.

The new allegations are the latest blow to Pruitt, 49, whose continued leadership of the environmental agency has been under fire since the revelation two weeks ago that he lived in a bargain-priced Capitol Hill condo tied to a fossil fuels lobbyist.

Senate Republicans on Thursday confirmed former coal industry lobbyist Andrew R. Wheeler as the second highest-ranking official at EPA. As the EPA's deputy administrator, Wheeler will be next in line if Pruitt is forced to resign or is fired.

EPA's inspector general is conducting at least five audits scrutinizing Pruitt's spending and other issues. The GOP-led House Oversight committee recently expanded its ongoing probe of Pruitt's travel spending to include his living arrangements. Pruitt has insisted that the $50 a night he paid for the condo was a fair market rate.

Chmielewski said he was listening on speaker phone during a call last year in which lobbyist Steven Hart complained that Pruitt had not even been paying that modest rent.

Hart is chairman and CEO of the powerhouse lobbying firm Williams & Jensen, which records show has several clients who have received favourable regulatory rulings from EPA under Pruitt.

On travel, Chmielewski said Pruitt told him and other EPA staffers the foreign countries he wanted to visit and instructed them to find official reasons for him to go. He said Pruitt also told them he wished to spend long weekends in his home state of Oklahoma and that they should come up with plausible explanations for taxpayers to foot the bill.

Pruitt also insisted they book flights on Delta, even though it was not the preferred air carrier for government travel, so that the administrator could accrue frequent flyer miles.

On a $120,000 trip to Italy, Chmielewski said Pruitt refused to stay in the hotel recommended by the U.S. embassy, leading to excess costs. Pruitt's chief of security spent an extra $30,000 to hire Italian security guards to supplement his already sizable EPA entourage.

The Associated Press reported last week that Pruitt's concern with his safety cost taxpayers about $3 million, as his swollen security team blew through overtime budgets and diverted officers away from investigating environmental crimes.

Though Wilcox has said the security costs are justified due to "unprecedented" death threats against Pruitt and his family, Democrats disclosed the existence of an internal EPA analysis on Wednesday that concluded there was not "any specific, credible, direct threat to the EPA administrator."

Chmielewski said after months of pressure he was removed from his job after he refused to retroactively sign off when Pruitt's top policy aide, Samantha Dravis, accompanied the administrator in first class on a trans-Atlantic flight back from Morocco.

Dravis, 35, resigned from EPA earlier this month. She was a close confidant of Pruitt's from Oklahoma who was hired at EPA with an annual salary of nearly $180,000.

Chmielewski said he was told that Pruitt wanted him gone so he could elevate another close aide from Oklahoma, 26-year-old scheduling director Millian Hupp, to his position as deputy chief of staff and boost her salary to $114,590, a raise of more than $28,000.

After the White House refused to sign off on the raise for Hupp, Chmielewski said Pruitt used a little known legal authority solely granted to the EPA administrator to push it through himself. Chmielewski said Pruitt also used his authority to increase the salary of his senior legal counsel, 30-year-old Sarah Greenwalt, by nearly $57,000, to $164,200 a year.

In a combative Fox News interview on April 4, Pruitt insisted he didn't approve the big raises and didn't know who did. Pressed by the interviewer on whether Hupp and Greenwalt were friends of his, Pruitt replied, "Well, they serve a very important person."

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