WASHINGTON — The head of the Environmental Protection Agency paid just $50 a night to stay in a Capitol Hill condominium linked to a prominent Washington lobbyist whose firm represents a roster of fossil fuel companies.

EPA Administrator Scott Pruitt paid for a single bedroom in the building on a leafy street about a block from the U.S. Capitol, staying for about six months in 2017 during nights he was in Washington. Records show three units inside the building are listed as belonging to a corporation co-owned by the wife of J. Steven Hart, the chairman and CEO of the powerhouse lobbying firm Williams and Jensen PLLC.

The firm's clients include Exxon Mobil Corp. and the major liquefied natural gas exporter Cheniere Energy Inc. — companies that have billions at stake in regulatory decisions over which Pruitt presides. Records show in at least one case Pruitt met in his EPA office with a lobbyist from Hart's firm while he was renting the room.

Justina Fugh, an ethics lawyer at EPA, told The Associated Press on Friday Pruitt's rental agreement allowed him to only pay for nights he occupied the room, totaling about $6,000 in payments over the term of the lease.

Fugh said she was first briefed by other EPA officials about the terms of lease on Thursday, shortly after ABC News first reported on Pruitt's prior living arrangements. Fugh said she was not asked to review the lease or issue a formal legal opinion on it, though she did not immediately see it as an ethical concern since Pruitt paid for the room.

Fugh said she was told Pruitt has since moved to another apartment, though she said she was not privy to any details about where the administrator is currently staying, who owns that property or what rate he is paying.

Inside the White House on Friday, staffers expressed frustration by the optics of Pruitt's living arrangements, which come on the heels of the dismissal of Veterans Affairs Secretary David Shulkin over ethical missteps.

But while officials in the West Wing are reviewing the seriousness of the questions around Pruitt, it was too soon to know if the EPA secretary would face harsh internal questioning or draw the ire of President Donald Trump, according to a White House official not authorized to speak publicly about private discussions.

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A Republican who previously served as the state attorney general of Oklahoma, Pruitt has long been a champion of the oil and gas industry. In the year he has served as the Trump administration's top environmental official, Pruitt has moved to scrap, gut or replace numerous environmental regulations opposed by the industry while boosting the continued burning of fossil fuels, which is the primary cause of climate change.

In December, Pruitt and members of his staff spent about $40,000 in taxpayer funds to fly to Morocco to help encourage the North African kingdom to import liquefied natural gas from the United States. Cheniere, the lobbying client of Hart's firm, is currently the only exporter of liquefied natural gas from the continental United States.

In a statement to The Associated Press on Thursday, Hart said Pruitt is a casual friend from Oklahoma who moved into the building in early 2017. Hart said he had no contact with Pruitt for many months, other than a brief exchange at the National Prayer Breakfast in February.

"Pruitt signed a market based, short-term lease for a condo owned partially by my wife," Hart said, according to a statement released by his firm. "Pruitt paid all rent owed as agreed to in the lease. My wife does not, and has not ever lobbied the EPA on any matters."

Hart's wife, Vicki Hart, is also a lobbyist, focusing on health care issues.

EPA's press office also did not respond to messages seeking comment Thursday or Friday about Pruitt's Washington living arrangements.

The $50 a night rate Pruitt paid is significantly less than advertised rates for rentals in the Capitol Hill neighborhood where the unit is located. One bedroom apartments listed for rent in the immediate area on Friday ranged between $1,600 and $2,500 a month, depending on amenities. Single rooms listed online for one-night rentals averaged about $120 a night.

Pruitt has been under increasing scrutiny for this frequent taxpayer-funded travel, which has included first-class airline tickets. Though federal regulations typically require federal officials to fly in coach, the EPA chief has said he needed to sit in premium seats due to security concerns.

After a series of recent media reports about questionable spending, Pruitt was one four high-ranking Trump officials who met separately with White House Cabinet Secretary William McGinley to discuss proper ethics practices.

The president is still said to be fond of Pruitt and has applauded the EPA secretary for his attention-grabbing dust-ups with environmentalist groups, according to the White House official and an outside Trump adviser.

Both a House oversight committee and the EPA's inspector general are now reviewing Pruitt's travel spending. Jeffrey Lagda, a spokesman for EPA's internal watchdog, said Friday that the office has been "made aware of the allegations related to Administrator Pruitt's living arrangements last year."

Pruitt's EPA travel has also often included weekend-long layovers at his home in Tulsa. The EPA chief is widely mentioned in Oklahoma as a possible successor to Sen. James Inhofe, the state's octogenarian GOP senator who is expected to retire at the end of his current term.

Among the clients at Hart's lobbying firm is OGE Energy Corp., an electricity company serving Oklahoma and Arkansas. According to federal disclosure reports, the company paid Williams and Jensen $400,000 in 2017 to lobby on issues that included EPA regulations on greenhouse gas emissions from power plants.

Copies of Pruitt's daily calendar obtained by the AP through a public records request show that Pruitt held a March 2017 meeting in his EPA office with OGE Chairman and CEO Sean Trauschke and company vice president Paul Renfrow. The meeting was arranged at the request of George Baker, a registered lobbyist from Hart's firm, who also attended.

In October, EPA announced it would rewrite the Clean Power Plan, an Obama-era regulation that sought to limit planet-warming carbon emissions from coal-fired power plants like those operated by OGE. EPA has also moved to scrap regulations cutting power plant emissions of such toxic substances as mercury, as well as tighter standards on dumps containing coal ash.

Records show Pruitt has had a long relationship with OGE. Campaign finance reports from Oklahoma show more than three dozen OGE executives donated to Pruitt's 2014 re-election campaign for state attorney general, even though he was running without a Democratic opponent. OGE chairman Peter Delaney contributed $3,500, while Trauschke kicked in $2,500 and Renfrow contributed $1,000.

Environmental groups pointed to news of Pruitt's living arrangements as further evidence he caters to polluters, and they renewed their calls for him to resign.

"Scott Pruitt got a sweetheart deal on a D.C. condo directly from a fossil fuel lobbyist, then wasted thousands in taxpayer dollars pushing that lobbyist's agenda on a trip to Morocco," said Michael Brune, the executive director of the Sierra Club. "This deal stinks like the swamp Scott Pruitt is mired in."