Two years ago, Kevin Chmielewski was a Trump campaign aide who was working tirelessly to ensure that the New York businessman became America’s 45th president. He even convinced Trump to hold a rally at his high school alma mater in Berlin, Md., where the candidate called him “a star” and demanded that he stand onstage beside him.

“I don’t know what they produce at this school, but this guy is a gem,” Trump declared, with his aide next to him. “He’s tough as hell. Whenever there’s a problem he runs right in — like full blast, just runs in — and he is a wild man.”

On Thursday, Chmielewski, who served as deputy chief of staff for operations at the Environmental Protection Agency until last month, became the latest Trump ally to wreak havoc within an administration he helped put in office, publicly alleging EPA Administrator Scott Pruitt engaged in spending excesses and questionable ethics decisions.

Five Democrats in the House and Senate detailed his accusations in a six-page letter that chronicled stays in boutique hotels that busted federal spending caps, frequent trips home to Oklahoma that Pruitt charged to taxpayers, and costly flights on Delta Air Lines aimed at maximizing his frequent-flier miles.

The letter to Pruitt from congressional Democrats, including Rep. Elijah E. Cummings (Md.) and Sen. Thomas R. Carper (Del.), included many details that had been previously reported by The Washington Post and other media. But it also provided a firsthand account of what happened behind closed doors at the EPA, including expenditures on his office that included a $43,000 soundproof phone booth and telling staff to line up events so that he could visit certain places at taxpayer expense.

Chmielewski met Tuesday with Democratic investigators and huddled Thursday with Republicans from the House Oversight and Government Reform Committee, according to staffers on Capitol Hill.

“The new information provided by Mr. Chmielewski, if accurate, leaves us certain that your leadership at EPA has been fraught with unethical and potentially illegal actions on a wide range of consequential matters that you and some members of your staff directed,” the Democratic lawmakers wrote in their letter to Pruitt, which requested a long list of documents from the agency.

EPA officials previously have dismissed Chmielewski as one of a group of “disgruntled” employees who were dismissed or re­assigned. Chmielewski has said he was removed from his position and placed on administrative leave after refusing to approve inappropriate expenditures.

“We will respond to Members of Congress through the proper channel,” EPA spokesman Jahan Wilcox said in a statement.

Pruitt has been under fire in recent weeks over several actions, including a discount rental agreement with a lobbyist on Capitol Hill, frequent first-class travel and stays in boutique hotels, and generous pay raises to two trusted aides.

Chmielewski claims that Pruitt often chose travel destinations based on a desire to visit particular cities or countries rather than official business, according to the letter. He said Pruitt also directed staffers to book flights on Delta, even when it was “not the federal government’s contract carrier for the route,” to accrue frequent-flier miles. Chmielewski also said Pruitt routinely asked his staff to “find reasons” for him to travel to Oklahoma so that he could remain in his home state for long weekends, often at taxpayer expense.

In addition, Chmielewski claimed that Pruitt “frequently stayed in hotels that exceeded the allowable U.S. government per diem” and that while planning trips to Italy and Australia — the latter trip was canceled — the EPA chief refused to stay at hotels recommended by the U.S. Embassy, even though the hotels suggested by embassy officials “had law enforcement and other U.S. resources on site.”

A current EPA official, who spoke on the condition of anonymity to speak frankly, said that Pruitt had pushed to stay in a boutique hotel in Australia but not in Italy, as Chmielewski has told investigators.

Pruitt repeatedly opted to stay in Sofitel chain hotels both domestically and overseas, according to multiple aides, even when those costs exceeded the allowed government per diem.

Chmielew­ski also claims that Pruitt’s chief of staff, Ryan Jackson, was excluded from scheduling meetings about the EPA leader’s travel after raising concerns about his expenditures, according to the letter.

Chmielewski is facing his own ethics issue at the EPA, though hardly on the scale of the problems facing Pruitt. An EPA lawyer confirmed that he has so far failed to file his financial disclosure form, as required by law. If Chmielewski does not file the form in the coming months, he can be fined $200 and potentially referred to the Justice Department for civil or criminal prosecution, the official said.

Separately, congressional Demo­crats are now probing Pruitt’s use of four separate agency email addresses since taking office. Agency lawyers have raised concerns that the EPA has not disclosed all the documents it would normally release to the public under federal records requests, according to an agency staffer. But Wilcox said the FOIA process encompasses each of Pruitt’s accounts.

Two Democrats on the Senate Environment and Public Works Committee — Carper and Jeff Merkley (Ore.) — sent a letter obtained by The Post Thursday that asked the EPA’s inspector general to probe the matter. The IG’s office declined to comment.

Pruitt’s four email addresses include one in the conventional agency format, pruitt.scott@ epa.gov, and three others: esp7@epa.gov, adm14pruitt@ epa.gov and sooners7@epa.gov, an apparent reference to the University of Oklahoma, whose football team Pruitt follows closely.

In an email, Wilcox said that “all accounts are searched before we respond to [any] FOIA request.”

“The EPA maintains three email accounts which are attributed to Administrator Pruitt: two are used by staff for calendaring and public correspondence; the third is used by the Administrator,” he added. “A fourth email account was created for use by the Administrator but was superseded and never used beyond three test emails.”

The new revelations came as President Trump signed an executive order on Thursday with almost no fanfare that aims to change the way the EPA determines whether states are meeting federal air-quality standards. The measure, which Trump did not mention during two separate appearances before reporters at the White House, imposes stricter deadlines for EPA approval of state plans and changes the way air pollutants are measured.

John Walke, who directs the clean air program at the advocacy group Natural Resources Defense Council, said that the executive order prescribes measures “intended to allow more air pollution, or abbreviated air quality reviews that risk more air pollution, or both.”

Trump originally had been scheduled to appear with Pruitt to sign the order last week, but that event was canceled after a series of reports about the EPA chief’s spending and management habits. On Thursday, Pruitt tweeted about the order, but was nowhere to be seen near the president.