His detail now is composed of at least 18 full-time agents who are with him whether he's on official business or off duty. Given Pruitt's busy travel schedule and frequent trips home to Oklahoma, many agents racked up so much overtime that they hit annual salary caps of about US$160,000.
Pruitt is among the most high-profile Cabinet members and one of the most divisive. In justifying his constant security, EPA officials have said he has received far more threats than previous administrators.
Another agency official told the Post in February that verbal confrontations with members of the public prompted Pruitt to begin flying first-class last year so there would be a buffer between him and the public, as recommended by the leader of the detail, Pasquale "Nino" Perrotta.
"Scott Pruitt has faced an unprecedented amount of death threats against him and his family," EPA spokesman Jahan Wilcox said when asked about Pruitt's security costs. "Americans should all agree that members of the President's cabinet should be kept safe from these violent threats."
In several emails obtained by the Post, EPA security officials made it clear last year that the administrator's extensive travel schedule put a strain on resources before the agency hired additional officers.
While Pruitt has maintained the public support of Trump in recent days - the President tweeted on Saturday that Pruitt has done "a great job"- some top White House aides have recommended that he be dismissed, given the intensifying reports about his ethics and management decisions. Even some political allies have questioned whether he should remain.