WASHINGTON — A high-ranking political staffer at the Environmental Protection Agency has told lawmakers he faced retaliation after pushing back against outsize 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 position 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 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 longtime 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: Sens. Tom Carper of Delaware, 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 EPA has been under fire since the revelation two weeks ago that he rented a bargain-priced Capitol Hill condo tied to a fossil fuels lobbyist.

Senate Republicans on Thursday confirmed former coal industry lobbyist Andrew 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.

The Senate confirmed Wheeler, 53-45. Three Democrats — Heidi Heitkamp of North Dakota, Joe Donnelly of Indiana and Joe Manchin of West Virginia — joined with Republicans to approve Wheeler.

The 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 favorable 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.