By Louise Radnofsky and Heidi Vogt 

WASHINGTON -- Embattled Environmental Protection Agency Administrator Scott Pruitt faces an all-day grilling on Capitol Hill on Thursday, as the White House weighs his performance amid allegations involving his spending habits and ethics.

Mr. Pruitt is under investigation for his spending on office furnishings, personnel moves, travel costs, security practices and the link between his housing and a lobbyist. The White House, inspector general of the EPA, House oversight committee and Government Accountability Office have been looking at these issues.

Travel issues alone have already felled two cabinet members: Tom Price at the Department of Health and Human Services and David Shulkin at the Department of Veterans Affairs.

Now Mr. Pruitt is at risk of ebbing support even among conservative backers, who have begun hedging their praise. They said he needs a strong performance on Thursday to shore up his position.

"I've been pleased with the job Administrator Pruitt has been doing -- rolling back regulations and restoring the EPA to its proper size and scope, but these latest reports are new to me," said Sen. James Inhofe (R., Okla.), a longtime ally who didn't specify which reports had drawn his concern.

President Donald Trump, a Republican, has stood by Mr. Pruitt, noting he has had success implementing the White House's deregulatory agenda. Under Mr. Pruitt's watch, the EPA has eased restrictions on power-plant emissions, suspended a clean-water rule advanced by Mr. Trump's Democratic predecessor, pulled out of the Paris agreement on climate change and championed a plan for more permissive auto-emissions standards.

"He has been a very key player in advancing the president's agenda but some of his transactions and transgressions against logic deserve explanation," said Ken Blackwell, who as domestic policy chief during Mr. Trump's transitionstrongly backed Mr. Pruitt for the EPA job. "It's extraordinarily important that he is transparent and comprehensive in his responses and that he measures up."

In his prepared testimony for his hearing in front of the House Energy and Commerce Committee panel, Mr. Pruitt doesn't address any of the issues that have sparked controversy, highlighting instead his effort to make a "more efficient and effective EPA."

In the past, Mr. Pruitt has indicated that aides made key decisions, not him, on pay increases for top advisers and his first-class airplane travel. He has also noted that his agency's ethics officer signed off on his lease agreement, which critics have said was improperly below market rates and had ties to an energy lobbyist. The ethics office has since said it is revisiting the issue.

An administration official said on Wednesday that Mr. Pruitt faced a "very consequential day," and that he had significant obstacles to overcome. "He's bleeding out support in Congress," the official said, calling that a "big telltale sign."

Press secretary Sarah Sanders said the White House is "evaluating these concerns and we expect the EPA administrator to answer for them."

The administrator's day will begin with an appearance in front of a subcommittee of the Energy and Commerce Committee. An aide for committee Republicans said GOP lawmakers had "legitimate oversight questions" as well as policy matters to discuss.

A Democratic spokesman said lawmakers would attempt to ask about a range of the reports that have dogged Mr. Pruitt, including his lease, air-travel costs and his expensive security detail for personal trips. "It's a lot to try to get in, in one hearing," the aide said. "He needs to account for the investigations."

The subcommittee is up against a hard deadline. In the afternoon, Mr. Pruitt is scheduled to appear before a House Appropriations subcommittee. A spokeswoman for Republicans on that committee said the expectation was that the hearing would be more tightly focused on the EPA budget, with the potential for lawmakers to raise particular issues of concern.

But a Democratic aide said they had discussed the back-to-back hearings with counterparts on the Energy and Commerce Committee and plan to divide up the gamut of topics they want to address. For instance, appropriations committee lawmakers are planning to focus on ethics issues specifically related to government spending, including the installation of a soundproof phone booth and claims of retaliation against staff who challenged Mr. Pruitt's decisions.

Republican senators have been especially vocal in expressing concerns about Mr. Pruitt in recent days. "You've got to respect taxpayer money -- you can't go around just spending it like it was dishwasher and acting like a big shot. You can't. That hurts the president. That hurts the boss. That hurts all of us," Sen. John Kennedy (R., La.) said.

Mr. Pruitt's allies are stepping up a defense of his service on several fronts.

Sen. Chuck Grassley, an Iowa Republican who has been critical of Mr. Pruitt for his handling of the renewable fuel standard, said he has no interest in seeing him dismissed in large part because of the time it would take to fill the position. He blamed Democrats for blocking nominees, saying they "filibuster everything."

Some governors have described Mr. Pruitt as a familiar figure who understands their issues, and who they want to see stay as a result.

"He's been accessible and responsive," said Republican Doug Burgum, the governor of North Dakota, on Wednesday. "He's from Oklahoma, so he understands the oil and gas industries, which is helpful," he said, also citing Mr. Pruitt's support for the state on regulatory water issues.

Other administration allies warn that cutting ties with Mr. Pruitt may encourage more criticism of other administration officials.

Mick Mulvaney, who is both White House budget director and interim head of the Consumer Financial Protection Bureau, is being criticized by Democrats for telling a group of bankers that, when in Congress, he "didn't talk to" lobbyists who failed to give him political donations. Mr. Mulvaney did say he would see any constituent from South Carolina, whether they were a contributor or not.

The president's nominee to take over the Veterans Affairs Department, Dr. Ronny Jackson, is trying to mitigate lawmakers' growing concerns about his practice regarding distribution of prescription medicines and management during his time as White House physician.

Ralph Reed, head of the Faith and Freedom Coalition, a conservative advocacy group, urged the White House to support Mr. Pruitt or risk inspiring attacks on other administration officials.

"He has been fiercely loyal to President Trump, has courageously advanced his agenda to create jobs and redress regulatory overreach, and has paid a high personal price for doing so," Mr. Reed said. "The White House is smart to stand by him. To do otherwise would undermine a good man and only serve to embolden the president's critics."

--Rebecca Ballhaus, Tim Puko and Kristina Peterson contributed to this article.

Write to Louise Radnofsky at louise.radnofsky@wsj.com and Heidi Vogt at heidi.vogt@wsj.com

(END) Dow Jones Newswires

April 25, 2018 19:46 ET (23:46 GMT)