Mr. Pruitt has faced criticism, and received a reprimand from his boss, for spending more than $107,000 of public money on first-class air travel. But he remains a favorite of Mr. Trump’s, and after the past week of White House turmoil — with the president dismissing his secretary of state and intimating that a greater shake-up may follow — Mr. Pruitt appears to have job security that could work to his advantage over time.
The endgame, say people who have spoken with Mr. Pruitt, is a possible run at the presidency in 2024 or later. “It was always known among elite Republicans that this guy had higher ambitions,” said Keith Gaddie, a professor of political science at the University of Oklahoma. “The question was just, ‘Does he want to be president, or does he want to be attorney general?’”
To jump from E.P.A. chief to any of those posts would be highly unusual for the head of a historically wonky, low-profile agency. “The take has always been that E.P.A. is where your political career goes to die,” said William K. Reilly, who headed the agency under President George Bush.
Even in Republican administrations, Mr. Reilly said, the job historically involved imposing regulations on polluting industries, which can create powerful enemies. “It’s the kind of job that if you do it right, you antagonize a lot of people — big industry, even your own president,” he said.
But Mr. Pruitt has flipped the script. As Oklahoma’s attorney general, he sued the E.P.A. 14 times, and he has spent the past year working to undo regulations that would have required farmers to restrict their fertilizer use; oil and gas firms to control global warming pollution from their wells; and Midwestern power plants to burn less coal.
“He has made a big splash,” Mr. Reilly said. “The mission he is on is not one that his predecessors at E.P.A. have recognized. And it could be a good strategy to win the constituency that elected the president.”
Mr. Pruitt’s precise political path forward is not certain. He is viewed as a likely candidate to run for a Senate seat in Oklahoma in 2020 if the incumbent, James Inhofe, retires. But it remains unclear if Mr. Inhofe, 83, will do so, and his office declined to comment. There is also speculation that Mr. Pruitt might jump in as a last-minute candidate in this year’s governor’s race.
When asked about its boss’s ambitions, Mr. Pruitt’s staff emphasizes that he is focused only on the job at hand. It also notes that the E.P.A. chief has made a significant effort to promote his work. “Administrator Pruitt has utilized a wide array of news outlets to advance President Trump’s agenda on regulatory certainty and environmental stewardship,” his spokesman, Jahan Wilcox, wrote in an email.
Some former E.P.A. chiefs noted that Mr. Pruitt’s unusual speed at attempting to dismantle regulations could mean that those efforts might not stand up to later legal challenges. “The policies he’s pushing play very well in his home state and with the base — but you can’t do them overnight,” said Christine Todd Whitman, who headed the E.P.A. in the George W. Bush administration and before that was the governor of New Jersey. “They’re getting rushed out. I don’t think the homework is being done. It makes for good sound bites, but they might not stand up legally.”
That might not affect Mr. Pruitt’s longer-term political aspirations, though. “Pruitt could be gone from E.P.A. the time that happens,” Ms. Whitman said.
Among the largest regulations Mr. Pruitt aims to roll back, at Mr. Trump’s direction, is an Obama-era clean water rule, known as Waters of the United States, which would have restricted the chemical fertilizers used by farmers. The rule has been particularly unpopular with the rural voters who make up the core of Mr. Trump’s base. This year, Mr. Pruitt announced he would freeze implementation of the rule and issue a more farmer-friendly version by the spring.
Last year, Mr. Pruitt made two trips to Iowa, a key campaign state in presidential elections, to talk about his agenda. In the summer, he met with farmers to tout his rollback of the clean water regulation. In December, he promised that the E.P.A. would not use regulations to curb the production of corn ethanol — an issue considered key for presidential candidates in Iowa.
Mr. Pruitt has also halted implementation of Mr. Obama’s climate change rules, which would have frozen construction of new coal-fired power plants, and has said he intends to propose a replacement rule this year. Last April, he spoke at a Pennsylvania coal mine, telling workers that “the regulatory assault is over.”
Behind the scenes, Mr. Pruitt has spent time with major political donors. Last year he met with Foster Friess, a Republican fund-raiser, and with investors connected to Sheldon Adelson, the party megadonor, according to meeting records obtained by The New York Times. He also met with Steven Chancellor, an Indiana coal executive and Republican fund-raiser, according to documents obtained by the Sierra Club and published by Politico.
“All of this is unusual,” Ms. Whitman said. “If you’re in a federal position, you should not appear to be campaigning.”
Were Mr. Inhofe, long known as Congress’s most vocal opponent of efforts to fight global warming, to retire, Mr. Pruitt would be a natural fit to try to win his Senate seat.
Mr. Pruitt, who keeps his watch set to the time in Oklahoma even when he is working on the East Coast, has traveled to his home state regularly. Last March through May he spent 43 out of 92 days in Oklahoma or traveling to or from the state, according to a report by the Environmental Integrity Project.
Mr. Pruitt’s rise to prominence in Oklahoma began during the eight years he managed and co-owned the Oklahoma City RedHawks, a minor league baseball team. He won a seat in the State Legislature and opened a small legal office, Christian Legal Services, to challenge government actions that he saw as compromising individual rights.
As an owner of the RedHawks, Mr. Pruitt ran television ads that featured himself promoting the team. They gave him statewide recognition and played a role in his 2010 race for attorney general, said Chris Wilson, an Oklahoma-based Republican strategist who worked on the presidential campaign of Senator Ted Cruz of Texas. “He had instant name recognition,” Mr. Wilson said.
As attorney general, Mr. Pruitt built close ties with the state’s oil and natural gas industry. A 2014 investigation by The Times found that energy lobbyists drafted letters for Mr. Pruitt to send to the E.P.A., on state stationery, outlining the economic hardship of environmental regulations on their industries.
The ties have paid off politically. Harold G. Hamm, who advised the presidential campaigns of Mr. Trump and Mitt Romney and is the chief executive of Continental Resources, an Oklahoma oil and gas company, was a co-chairman of Mr. Pruitt’s 2013 re-election campaign.
Mr. Pruitt’s tenure at the E.P.A. has already proven popular with the oil and natural gas industry. His proposals have been aimed at loosening regulations, particularly an Obama-era rule that would have required companies to rein in emissions of methane, a powerful greenhouse gas, from new oil and gas wells. (A federal appeals court later ruled that the effort was illegal.)
Energy companies were also delighted when Mr. Pruitt flew to Morocco in December, in an unusual trip aimed at promoting exports of natural gas. That trip received criticism, though, in part because the E.P.A. does not oversee natural gas exports.
The E.P.A.’s inspector general is investigating some of Mr. Pruitt’s trips, including the one to Morocco and some to Oklahoma, but it is not clear whether that will be a liability. “It’s not great, but it’s not fatal,” Michael McKenna, a Republican energy lobbyist who advised the Trump campaign, said referring to Mr. Pruitt’s airline expenses. “None of the old rules seem to apply,” he said. “The current president seems to have erased a lot of them.”