WASHINGTON—Scott Pruitt, the embattled administrator of the Environmental Protection Agency, resigned Thursday after allegations of ethical lapses and improper spending overshadowed his aggressive campaign to roll back Obama-era environmental rules.

President Donald Trump, who announced Mr. Pruitt’s departure in a tweet, said Mr. Pruitt’s deputy, Andrew Wheeler, would become acting EPA administrator on Monday.

A former lobbyist for the coal industry, Mr. Wheeler is expected to continue Mr. Pruitt’s push to position the EPA as an agency that avoids stifling business investment or opportunity while seeking to protect the environment and enforce environmental laws, after years in which many Republicans complained the agency overreached in its regulations.

Mr. Pruitt had become a lightning rod for administration critics, fueled not only by his approach to environmental policy but a string of controversies involving his travel, potential employment for his wife, his living arrangements in Washington and spending at the agency.

“I have accepted the resignation of Scott Pruitt as the Administrator of the Environmental Protection Agency. Within the Agency Scott has done an outstanding job, and I will always be thankful to him for this,” Mr. Trump tweeted.

The president stood by Mr. Pruitt for months, despite the growing ethical allegations raised by both Democrats and Republicans. Mr. Trump, a Republican, frequently cited the EPA chief’s success in rolling back regulations advanced by Mr. Trump’s Democratic predecessor. Mr. Pruitt withdrew an Obama-era rule requiring reduced carbon emissions from coal-burning power plants, and was considered instrumental in persuading Mr. Trump to pull out of the Paris climate accord.


Mr. Pruitt also pushed to sharply reduce the EPA’s oversight powers. Last month, he moved to limit the agency’s ability to block permits issued to mining, real-estate and other developers to dump waste into waterways.

Mr. Trump said Thursday that Mr. Pruitt had done an “outstanding job inside of the EPA” but acknowledged “obviously, the controversies.” The president told reporters traveling with him to Montana for a campaign-style that in his view there had been “no final straw” and that Mr. Pruitt had decided over the last couple of days that “he was a distraction.”

As recently as Wednesday, Mr. Pruitt attended a picnic on the White House lawn for military families, along with several other cabinet members, and was recognized by Mr. Trump in his prepared remarks. Mr. Pruitt and his guests took selfies and asked for someone to take a shot of them posed against a backdrop of the building.

An EPA spokesman, Jahan Wilcox, confirmed Thursday that Mr. Pruitt had submitted a letter of resignation to Mr. Trump.

In the letter, Mr. Pruitt wrote that it was “extremely difficult for me to cease serving you in this role first because I count it a blessing to be serving you in any capacity, but also, because of the transformative work that is occurring. However, the unrelenting attacks on me personally, my family, are unprecedented and have taken a sizable toll on all of us.”


Mr. Pruitt had continued to enjoy the backing of the president for months, even as some former supporters backed away.

His work earned him a reputation as one of the most loyal cabinet members and one of the most effective at executing Trump administration philosophy. Mr. Trump in the past referred to him privately as “my lawyer,” one White House official said.

But White House officials expressed increasing misgiving about the scandals surrounding the former Oklahoma attorney general. And he alienated some in the administration by making known his desire to succeed Jeff Sessions as attorney general, should Mr. Sessions step down or be fired, according to a White House official.

About three months ago, White House Chief of Staff John Kellyprivately told the president that he should oust Mr. Pruitt in the face of mounting controversies, according to a White House official. Mr. Trump ignored the advice.


Mr. Pruitt’s exit is the latest high-level departure from the administration. In the past year, the president ousted two cabinet secretaries, Secretary of State Rex Tillerson and Veterans Affairs chief David Shulkin, and accepted the resignation of a third, Health and Human Services Secretary Tom Price. He also removed national security adviser H.R. McMaster.

Earlier this week, a former staffer said Mr. Pruitt and his staff omitted, altered or removed from his official calendar potentially controversial meetings and phone calls, some with industry executives. Such changes could be considered an illegal falsification of government records.

In mid-June, the federal government’s ethics watchdog pushed the EPA’s in-house investigators to expand and accelerate their inquiry into allegations against Mr. Pruitt, to include additional claims about Mr. Pruitt’s use of subordinates’ time to complete personal errands for him, as well as to seek business opportunities for his wife, including as a Chick-fil-A franchisee.

The EPA inspector general was already reviewing allegations against Mr. Pruitt including those involving travel practices and security costs, personnel moves at the agency and how he obtained rental housing connected to a Washington lobbyist.


The White House began a review of Mr. Pruitt’s activities in April after news reports that in 2017 he stayed in a townhouse on Capitol Hill co-owned by the wife a top energy lobbyist, J. Steven Hart. The White House was reviewing the arrangement and whether Mr. Pruitt was paying below-market rates to stay at the house.

Several House and Senate committees had also been investigating Mr. Pruitt’s conduct, including taking extensive testimony from current and former aides. Democratic lawmakers who had been pushing for Mr. Pruitt’s departure were swift, and blunt, in their reaction Thursday. “It’s about time,” said Rep. Tim Ryan (D., Ohio.)

Sen. Jim Inhofe (R., Okla.), a longtime ally of Mr. Pruitt’s, praised Mr. Pruitt’s work at the agency but said that Mr. Wheeler had worked for him for 14 years and had “an impeccable reputation” and would be a “strong leader” at the agency.

Mr. Pruitt rose to national prominence years before he joined the Trump administration. After becoming Oklahoma’s attorney general in 2011, he led a coalition of conservative states in lawsuits against the federal government.

The coalition won major victories challenging some Obama administration policies all the way to the Supreme Court. His suits changed how former President Barack Obama’s health-care overhaul works, and he won a stay that put Mr. Obama’s signature climate-change policy, the Clean Power Plan, on hold.

That made him a darling of conservative groups, some energy companies and some prominent Republican boosters. Chief among them was oil magnate Harold Hamm, the founder and CEO of Continental Resources Inc. in Oklahoma City, who became a top energy adviser to Mr. Trump.

A former state legislator and owner of a minor-league baseball team, Mr. Pruitt was considered a climate-change skeptic. He has since said he accepts that climate change is happening, but questions how severe it might be and government’s role in fighting it.

He made climate policy less of a priority at the EPA. He sought to remake the agency by shrinking and reorganizing its staff, and rolling back a number of water and air rules that affected energy producers, farmers, auto makers, and others.

Mr. Pruitt’s policies made him a target for environmental groups and liberals before he took office, but criticism grew over how he ran the agency and spent money.

He met extensively with the companies his agency regulated, but not environmental groups. He used agency money repeatedly to fly back to his home state. And he flew unannounced to Morocco for several days to promote national-gas consumption, which critics charged was far outside the EPA’s mission. More allegations surfaced in recent weeks involving his efforts to find his wife employment in Washington.

At a Senate hearing in May, Mr. Pruitt reiterated past defenses that some of the accusations of management missteps and improper spending were false—and that others were justified by policy needs or properly cleared by agency officials.

—Heidi Vogt, Timothy Puko, Peter Nicholas and Kristina Peterson contributed to this article.

Write to Louise Radnofsky at louise.radnofsky@wsj.com