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Environmental Protection Agency chief Scott Pruitt’s concern with his safety came at a steep cost to taxpayers, as his swollen security detail blew through overtime budgets and at times diverted officers away from investigating environmental crimes to protect him.

Altogether, the agency spent millions of dollars for a 20-member full-time security detail that is three times the size of his predecessor’s part-time security contingent.

New details in Pruitt’s expansive spending for security and travel emerged from agency sources and documents reviewed by The Associated Press. They come as the embattled EPA leader fends off allegations of profligate spending and ethical missteps, related to his staff and housing arrangements, that have imperiled his job.

President Donald Trump on Friday defended Pruitt. "Do you believe that the Fake News Media is pushing hard on a story that I am going to replace A.G. Jeff Sessions with EPA Chief Scott Pruitt, who is doing a great job but is TOTALLY under siege?" Trump wrote in a Friday morning tweet.

"Do people really believe this stuff?" he added. "So much of the media is dishonest and corrupt!"

The post came a day after multiple administration officials familiar with Trump's thinking told NBC News that the president had been considering, as recently as last week, replacing Sessions with Pruitt, who previously served as the attorney general of Oklahoma. The news was first reported by CNN.

Trump met with Pruitt on Friday at the White House, a White House official confirmed to NBC News. But the purpose of the meeting, the official said, was to discuss fuel economy standards for passenger cars and trucks.

White House Press Secretary Sarah Huckabee Sanders, at a press briefing Friday, praised Pruitt but said the administration was "continuing to review any of the concerns that we have."

"No one other than the president has the authority to hire and fire members of his Cabinet. It’s a decision that he’ll make, and right now I don’t have any personnel announcements," she added.

In recent weeks, Pruitt has been the subject of multiple negative reports that have raised ethics concerns about his frequent first-class travel, his sweetheart deal to rent a condo from the wife of an energy lobbyist, and big pay raises reportedly afforded to top aides without White House approval.

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Shortly after arriving in Washington, Pruitt demoted the career staff member heading his security detail and replaced him with EPA Senior Special Agent Pasquale “Nino” Perrotta, a former Secret Service agent who operates a private security company. An EPA official with direct knowledge of Pruitt’s security spending says Perrotta oversaw a rapid expansion of the EPA chief’s security detail to accommodate guarding him day and night, even on family vacations and when Pruitt was home in Oklahoma.

The EPA official spoke on condition of anonymity for fear of retaliation.

The EPA official said there are legitimate concerns about Pruitt’s safety, given public opposition to his rollbacks of anti-pollution measures.

But Pruitt’s ambitious domestic and international travel led to rapidly escalating costs, with the security detail racking up so much overtime that many investigators hit annual salary caps of about $160,000. The demands of providing 24-hour coverage even meant taking some investigators away from field work, such as when Pruitt traveled to California for a family vacation.

The EPA official said total security costs approached $3 million when pay is added to travel expenses.

More allegations emerged Thursday, when CBS News reported that Pruitt, just weeks after he was confirmed to the post, wanted to use his vehicle's sirens and lights to get through Washington traffic. When his lead security agent refused the request, explaining that he couldn't use them unless there was an emergency, the EPA reassigned him, CBS News reported.

The New York Times also reported Thursday that several EPA officials, some of them senior, had been sidelined after questioning Pruitt.

Pruitt has faced continued fallout over reports that for the first six months he was in Washington, he leased a Capitol Hill condo tied to a lobbyist that did business with the EPA and paid just $50 a night, only for the nights he stayed there. The news was first reported by ABC News, which also reported that the townhouse is co-owned by Vicki Hart, the health care lobbyist wife of J. Steven Hart, an energy lobbyist. By Friday, news had emerged that Pruitt was supposed to live in the Harts' condo for only six weeks and that, according to Politico, the Harts pushed him out and changed their locks. Politico reported a day earlier that Pruitt had also fallen behind on his cut-rate rent payments.

And in February, Pruitt drew criticism after it was revealed he and his aides spent more than $90,000 for trips in early June and $15,000 to fly home during the weekends to Oklahoma between March and May of 2017. Pruitt traveled mostly first class, despite federal regulations requiring federal officials to fly in coach. Two month earlier, in December, Pruitt and members of his staff spent roughly $40,000 in taxpayer funds to fly to Morocco to help encourage the country to import liquefied natural gas from the United States.

In addition, The Atlantic reported that Pruitt had bypassed the White House to give two top aides, Sarah Greenwalt and Millan Hupp, substantial pay raises.

In an interview with Fox News on Wednesday, Pruitt justified the condo arrangement, saying that it was "like an Airbnb situation" and that he did not do anything improper. He also said he was unaware of the salary increases and planned to review the decision internally.

Despite Trump's expressions of support for Pruitt, others within his administration are said to have advocated for Pruitt's ouster.

The Wall Street Journal, citing a White House official, reported Friday that Chief of Staff John Kelly is among the White House aides who are convinced that Pruitt should leave the administration.

However, that official told The Wall Street Journal, Trump is not ready to remove him given Pruitt's success in pushing the president's deregulatory agenda.

As the head of the EPA, Pruitt is Trump's point man for the administration's plan to roll back environmental regulations — many of which were put in place by the Obama administration and opposed by industry lobbyists — while boosting the continued burning of fossil fuels, which scientists have concluded is the primary cause of climate change.

On Friday, House Minority Leader Nancy Pelosi, D-Calif., called on Pruitt to resign, joining a handful of Democratic senators, and 64 House Democrats, who have also urged him to step down.

"EPA Administrator Scott Pruitt's tenure has been a part of the Trump Administration’s culture of corruption, cronyism and incompetence. Pruitt must resign," Pelosi said in a statement, adding that he "has displayed a staggering ethical blindness."

At least three House Republicans — Reps. Elise Stefanik of New York, and Carlos Curbelo and Ileana Ros-Lehtinen, both of Florida — have also called on Pruitt to resign.