Washington • In mid-September, the Environmental Protection Agency chief’s director of scheduling and advance contacted the Trump International Hotel in Washington with an unusual request. Millan Hupp wanted to know how much the hotel would charge EPA Administrator Scott Pruitt for purchasing one of its used mattresses.

Hupp’s search for a discount “Trump Home Luxury Plush Euro Pillow Top” mattress, which she detailed in a recent interview with congressional investigators, was one of several unusual tasks she performed for the administrator. The senior aide also scouted apartments for her boss in some of the District’s hippest neighborhoods and helped arrange his family vacation to California over the New Year’s holiday so that the Pruitts could watch the Oklahoma Sooners play in the Rose Bowl.

Pruitt’s push to enlist a subordinate in his quest for cheap bedding — outlined in a letter Monday from two of the top Democrats on the House Oversight and Government Reform Committee, Elijah Cummings of Maryland and Gerald Connolly of Virginia, to the panel’s chairman, Trey Gowdy, R-S.C. — was one of several efforts he has made to minimize his personal expenses since moving to Washington, D.C.

According to two former EPA employees, Pruitt instructed aides last year to arrange work-related trips in August so that he could either be on the road or working from his home in Tulsa rather than pay for an apartment rental in the District that month.

The Oversight Committee is conducting a probe of several spending and management decisions Pruitt has made since taking the helm of the EPA. Those include first-class travel taken as a security precaution until earlier this year and an unusual rental arrangement he had with a lobbyist for nearly half of 2017, in which he paid $50 a night to stay at her Capitol Hill condo — but only on the nights he slept there.

“If Ms. Hupp’s statements to the Committee are accurate, Administrator Pruitt crossed a very clear line and must be held accountable,” Cummings and Connolly wrote.

Asked about the matter Monday, EPA spokesman Jahan Wilcox said in an email, “We are working diligently with Chairman Gowdy and are in full cooperation in providing the Committee with the necessary documents, travel vouchers, receipts and witnesses to his inquiries.”

Hupp described her work for Pruitt on an array of personal tasks, including booking nonwork flights with his personal credit card, during a closed-door interview with Republican and Democratic aides from the House panel on May 18. Hupp said she recalled that Pruitt “has spoken with someone at the Trump hotel who had indicated there could be a mattress he could purchase, an old mattress he could purchase.”

Amanda Gonzalez, a spokeswoman for Gowdy and the Oversight Committee, said the committee will wait until the end of its investigation to release its findings. “Selectively releasing portions of witness interview transcripts damages the credibility of our investigation and discourages future witnesses from coming forward,” she said.

White House press secretary Sarah Huckabee Sanders was asked Monday about Pruitt’s use of an aide to inquire about a mattress from the Trump International Hotel, located just across the street from the EPA headquarters. The administration is “certainly looking into the matter,” she said, adding, “I couldn’t comment on the specifics of the furniture used in his apartment.”

While hotel staffers help guests buy Trump-branded furnishings, used mattresses do not appear to be available. A receptionist last week referred a Washington Post reporter to Tempur-Sealy corporate offices, where Stearns and Foster sells via mail order the same mattress found in rooms at the Trump hotel. A standard queen mattress, without a box spring or any other accompanying items, costs $1,399 before tax and shipping.

Trump-branded mattresses used to be available more widely when they were manufactured by Serta and sold in department stores such as Macy’s. But Serta, along with other companies that had paid to license Donald Trump’s name, halted that merchandising business once his political rhetoric during the 2016 presidential campaign sparked controversy. Serta terminated its partnership in July 2015.

Three years earlier, Trump himself had touted the bedding line, tweeting on Oct. 18, 2012: “My Trump Home Mattress Collection by Serta is setting records — they are really phenomenal. You can order them at http://www.serta.com.”

Hupp initially phoned the hotel managing director on Sept. 14 about getting a used mattress, rather than explain her objective in writing, according to emails released under a Freedom of Information Act request by the Sierra Club. In an email that day, Hupp identified herself as one of Pruitt’s employees and said she was “hopeful you could give me a quick call when you have a couple minutes.”

Among the other personal tasks Hupp told congressional investigators she performed for Pruitt, she said she “assisted him in booking travel to the Rose Bowl” over his winter vacation with his family.

She also provided the committee with new details on how she conducted a housing search for him “over the course of a couple of months,” which ultimately entailed moves that his wife and he made to two separate apartments in Washington. While the administrator testified before a House panel that Hupp performed the apartment hunt “on personal time,” Hupp said she did some of it during work hours and used her official agency email at times.

Asked whether she took leave from work when she occasionally looked during office hours at properties for the Pruitts, Hupp told committee staffers, “I did not.”

Federal rules prohibit subordinates from providing free services to their bosses.