WASHINGTON (AP) — Environmental Protection Agency chief Scott Pruitt faces potentially make-or-break hearings Thursday on Capitol Hill, where he is expected to be peppered with questions about spending and ethics scandals that have triggered bipartisan calls for his ouster.

Pruitt was scheduled to testify about his agency's budget in back-to-back hearings before two House subcommittees.

The public grilling comes amid notable erosion in support for Pruitt among fellow Republicans after a nearly monthlong hammering of negative headlines about outsized security spending, first-class flights and a sweetheart condo lease.

President Donald Trump has continued to stand by his EPA chief, but behind closed doors, White House officials concede Pruitt's job is in serious jeopardy. In the last week, a growing list of Republican lawmakers has joined the chorus of Democrats calling for new investigations into Pruitt's actions.

Republican Sen. John Kennedy of Louisiana said Pruitt's behavior has begun to hurt Trump's credibility, as well as the Republican Party generally.

"I don't mean to be too harsh, but you can't just go around acting like a big shot, and you can't go around seeing how close you can come to the line, and you can't go around disrespecting taxpayer dollars," Kennedy said Tuesday. "It shouldn't be tolerated. That's part of the swamp that we're trying to clean up."

Pruitt has faced a steady trickle of revelations involving pricey trips in first-class seats and unusual security spending, including a $43,000 soundproof booth for making private phone calls. He also demanded 24-hour-a-day protection from armed officers, resulting in a swollen, 20-member security detail that blew through overtime budgets and racked up expenses approaching $3 million.

White House press secretary Sarah Huckabee Sanders said officials were "evaluating these concerns and we expect the EPA administrator to answer for them."

Pruitt's prepared testimony for the House environment subcommittee made no reference to ethics issues. Released ahead of the hearing, Pruitt promoted his prior accomplishments and remarked on his priorities for the coming budget year.

EPA spokesman Jahan Wilcox said congressional hearings were an opportunity to describe the agency's accomplishments, which he said included efforts to repeal the Obama administration's clean power plan, eliminating lead and reducing staffing levels at EPA.

Pruitt in the past has often sought to deflect questions about any missteps by blaming his subordinates.

Asked about his frequent use of premium-class airfare in February media interviews, Pruitt said, "I'm not involved in any of those decisions." The administrator said his security chief made the decision for him to fly in first class after an unpleasant interaction with another traveler raised safety concerns.

Pruitt's troubles began in earnest last month, when ABC News first reported he had leased a Capitol Hill condo last year for just $50 a night that was co-owned by the wife of a veteran fossil fuels lobbyist whose firm had sought regulatory rollbacks from EPA.

Both Pruitt and the lobbyist, Steven Hart, denied he had conducted any recent business with EPA. But Hart was forced to admit last week he had met with Pruitt at EPA headquarters last summer after his firm, Williams & Jensen, revealed he had lobbied the agency on a required federal disclosure form.

EPA's press office has declined to discuss the meeting.

Thursday's hearings will be Pruitt's first major appearance since a Fox News interview in early April that was widely considered to be disastrous within the West Wing.

Pressed on reports of significant raises awarded to two close aides he had brought with him to EPA from Oklahoma, Pruitt denied having any role in the decision. Documents later showed Pruitt's chief of staff signed off on the pay increases, indicating he had the administrator's consent.

A lawyer and former Oklahoma attorney general, Pruitt is known to meticulously prepare for congressional hearings, with his office schedule showing he often blocks off hours huddled with top political aides.

An administration official confirmed that Pruitt declined an offer of White House assistance in preparing for the latest congressional hearings. The official spoke on condition of anonymity to discuss sensitive internal conversations.

Environmental groups opposed to Pruitt's efforts to gut anti-pollution regulations have attempted to ramp up the pressure this week, paying for TV ads attacking Pruitt to be aired during the "Fox & Friends" morning show on Fox News. Trump is known to be a devoted viewer.

A union representing EPA employees also rallied Wednesday outside the agency's headquarters in Washington to denounce Pruitt's leadership.

Republican Sens. John Barrasso of Wyoming and John Thune of South Dakota said Pruitt faces "serious questions" about his use of taxpayer money.

"I want to make sure taxpayers are getting value for their dollars, make sure money is being spent appropriately. So there continue to be serious questions," said Barrasso, chairman of the Senate Environment and Public Works Committee. "We'll see what comes out of the hearings."

___

Associated Press writers Zeke Miller and Matthew Daly contributed to this report.

___

Follow Associated Press environmental reporter Michael Biesecker at http://twitter.com/mbieseck