For more than a decade, Sen. James M. Inhofe has raged against the scientific consensus that humans are fueling climate change, calling it “the greatest hoax” ever perpetrated on Americans. The Oklahoma Republican has blasted the Environmental Protection Agency as an “activist organization” that has unfairly burdened everyone from farmers to fossil-fuel companies.

Now the man critics once dismissed as a political outlier has an unprecedented opportunity to shape the nation’s energy and ­environmental policies. And he has helped populate the upper ranks of the agency he has derided with several of his closest confidants.

At least half a dozen former aides to Inhofe — and counting — have been hired into top positions at the EPA and the White House. The chief of staff and deputy chief of staff to EPA Administrator Scott Pruitt, a fellow Oklahoman and longtime friend of Inhofe, spent years working for the senator. Pruitt’s senior advisers on air, climate and legal issues are Inhofe alumni. In addition, two former Inhofe aides have become top domestic and international energy and environmental advisers to President Trump.

“It gives me a level of comfort to know that we have a bureaucracy that’s actually going to be serving instead of ruling,” Inhofe said in an interview this week, describing his former staffers as qualified professionals who will protect the environment. “They are going to be very realistic. They’re going to do it in a way that will not be punitive. The previous administration was almost looking for ways to punish people.”

Comforting is not how many of Inhofe’s longtime opponents would describe the changes.

(Sarah Parnass/The Washington Post)

“Inhofe was like the original climate-denier in chief. He was one of the first people spouting this gibberish — fact-free but dangerous gibberish,” said Gene Karpinski, president of the League of Conservation Voters. “Now he and his cronies have far more reach and are far more dangerous than they’ve ever been. . . . That’s good news for the polluters but horrible news for public health.”

Inhofe, 82, has been in the Senate since 1994 and has served as the top Republican on the Senate Environment and Public Works Committee for 12 out of the past 14 years. For much of that time, he has been one of the nation’s most powerful climate-change skeptics, even writing a book in 2012 attacking the science around global warming, which most of the world has accepted as a serious and urgent threat.

His most high-profile assault on climate science — one President Barack Obama mocked multiple times — came on a cold day in February 2015, when he stood on the Senate floor, fresh snowball in hand, to suggest that Earth could not be warming in any dangerous way, given the winter weather outside.

Ryan Jackson, Inhofe’s former chief of staff, helps account for part of why so many of the senator’s aides are now helping guide the administration’s policymaking. Jackson, who helped shepherd Pruitt’s nomination, then became the administrator’s chief of staff and started tapping his former colleagues for top agency posts.

While nearly every federal department has been undergoing major changes since Trump took office in January, few have seen as rapid and dramatic a shift as the EPA. It has already scrapped a request for data about methane emissions that could have paved the way for tighter restrictions on more than 15,000 U.S. oil and gas firms, and Trump has directed the agency to roll back a rule designed to protect 60 percent of the nation’s water bodies.

On Wednesday, Pruitt is set to announce plans to revisit fuel standards the Obama administration set for cars and light trucks that will be built five years from now. And his staff is preparing to unwind the centerpiece of Obama’s effort to combat climate change — the “Clean Power Plan,” which limits carbon dioxide emissions from power plants.

‘The Inhofe brigade’

To carry out the changes Trump has promised, namely setting the EPA on a more minimalist course that will constrain federal authority over the environment, the new administration has recruited a group of conservative stalwarts who have spent years working to advance Inhofe’s objectives. At times, some of them have worked directly for the mining, oil and utility companies that they are now charged with regulating.

“The Inhofe brigade has landed, secured the beach and is moving inland with precision as well as speed,” said Stephen Brown, vice president for government affairs at Tesoro, a major oil refiner.

What exactly will that invasion look like?

Those behind it are, for the most part, not nearly as colorful or outspoken as their former boss, even as they share many of his views and objectives.

Congressional aides of both parties described Jackson as one of the most soft-spoken managers on Capitol Hill. Amanda Gunasekara, who will advise the EPA administrator on air and climate issues, had been working for Inhofe less than a month when he asked her to hand him a snowball on the Senate floor two years ago to prove that global warming had not snuffed out winter altogether. Andrew Wheeler, a front-runner to serve as Pruitt’s No. 2, served the senator for 14 years before going on to lobby for the coal giant Murray Energy, Xcel Energy and the Nuclear Energy Institute. A few former Inhofe aides — Wheeler, as well as George Sugiyama and Michael Catanzaro, who is now in the White House — have worked at the EPA before.

Inhofe and his aides have shown legislative savvy. Even as the senator decried the Obama administration’s work on carbon dioxide emissions from power plants, mercury pollution and smog as burdensome for business and possibly illegal, Inhofe and his staff struck major deals on bipartisan issues including chemical safety, transportation and water infrastructure.

Joseph Stanko, who heads government relations at the law firm Hunton & Williams, said the combination of Republicans’ electoral success last year and the Obama administration’s aggressive use of executive authority has given conservatives a rare opening.

“It’s a real confluence of there being a philosophical alignment between Senator Inhofe and the administration, the Republicans holding both branches of government and there being, for lack of a better word, opportunity created by the prior overreach,” said Stanko, whose clients include Koch Industries, Southern Co. and the Electric Reliability Coordinating Council.

‘War’ on environmentalism?

Opponents see the Trump administration and the influx of Inhofe staffers to the EPA as the early steps in the dismantling of crucial regulations Obama put in place to combat climate change.

“The EPA was a staunch defender of the environment and supporter of climate action under the Obama administration,” said Michael Mann, a climate scientist at Pennsylvania State University. “It is now instead being wielded by the fossil-fuel interests who are running the Trump administration as just another weapon in their war on environmental protection and climate action.”

Trump wasn’t Inhofe’s first, or even second, choice for president last year. Initially, Inhofe endorsed his Senate colleague Marco Rubio (Fla.) in the GOP primaries, then, after he dropped out, Ohio Gov. John Kasich. But Inhofe then pivoted to Trump and began forging ties with the campaign through his friend and fellow senator Jeff Sessions (R-Ala.), advising Trump on defense and regulatory issues.

The dominance of Inhofe’s staffers reflects not just an ideological shift but the fact that even an administration of outsiders needs some insiders to help run the place. Inhofe remains extremely close with his former aides, whom he teasingly calls “has-beens.”

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Pruitt, like Inhofe, is determined to transfer some of the power his agency has amassed to the states. Earlier this month, a Wall Street Journal columnist described Pruitt, in a nod to the constitutional bent of the late Justice Antonin Scalia, as “an EPA originalist.” Privately, according to aides, the administrator relished the moniker. As Oklahoma attorney general, Pruitt sued the agency he now heads numerous times, often making the argument that the Obama administration had overstepped its legal authority.

Pruitt, who caused an uproar last week in a CNBC interview when he questioned whether carbon dioxide emissions are the primary driver of climate change, has made it clear he plans to focus the agency on more-traditional pollutants. His goals include minimizing lead exposure from drinking water — an issue on which Inhofe joined forces last year with then-Sen. Barbara Boxer (D-Calif.), despite opposition from House Republicans — and cleaning up contamination in Super­fund and contaminated industrial sites.

“Finally, we have someone in there that’s not going to be harassing the public with punitive regulations,” Inhofe said of Pruitt and his former staffers. “What I want them to do is to do what they are supposed to be doing — be concerned about the environment, the water, the air. . . . I’d like to see an EPA there to actually serve people and make life better for them.”

While it will take months to finalize the EPA’s budget for the coming fiscal year, the White House is contemplating significant reductions that could complicate Pruitt’s task and gut the agency. Two people briefed on the matter said the EPA budget proposal could be as low as $5.6 billion, down from the most recently enacted budget of $8.1 billion, a roughly 30 percent cut. Deep cuts could prompt unrest among employees, many of whom remain skeptical of the new administration and its motives, and eliminate staffers Pruitt and his senior advisers would need to accomplish their priorities.

Those include not just redoing Obama-era rules but possibly reexamining the way the EPA conducts its scientific assessment of health risks and other factors that underpin the regulations it issues.

“When I talk to people on the left, they are both happy that all these Inhofe people are there but also simultaneously scared,” said Dimitri Karakitsos, who left his post as Inhofe’s senior committee counsel in October to join the firm Holland & Knight as a partner.

They are relieved, he said, because the new appointees have shown a willingness to broker compromises on thorny issues. But, Karakitsos added, “the reason why I think they are scared is because it’s a really smart, thoughtful group that’s over there,” one that is not going to put out rules “on a whim that are easily undone.”

A Senate Democratic aide who has worked with many of the former Inhofe staffers agreed. “These are folks who are very capable. They know the agency and its programs,” said the staffer, who asked for anonymity to speak frankly. “They’re smart and hard-working, and they certainly could dismantle the programs if they were asked to do that. But the question is how they will react if they’re asked to do that.”