Mr. Pruitt has been under fire for his travel since The Washington Post reported that he routinely flies first or business class, and that he and top aides had spent more than $90,000 on airfare in the first few weeks of June alone.

Jahan Wilcox, a spokesman for the E.P.A., initially issued a statement that said that Mr. Pruitt had a “blanket waiver” to fly first class out of concern for his security. Mr. Wilcox later amended that to say that the E.P.A. did in fact submit a waiver for each trip.

According to the General Services Administration’s regulations for travel by federal employees, “blanket authorization” of anything other than coach-fare travel is barred except for reasons related to a disability or special need, and authorization for first-class travel is given on a “trip-by-trip” basis.

Mr. Pruitt has long been a target of criticism from Democrats, who last week asked the E.P.A.’s inspector general to expand an existing investigation into the administrator’s trips. But the issue of first-class travel has also struck a nerve with a handful of Republicans.

“I’m surprised at the expense of it,” Senator Shelley Moore Capito of West Virginia said in an interview last week. “Good stewardship of the federal dollar is important to me, and it should be to him.”