President Donald Trump is carrying out the most aggressive rollback of federal environmental rules since at least the Reagan administration.

And he’s just getting started.

In just 40 days, Trump has made it easier for coal miners to dump their waste into West Virginia streams, ordered the repeal of Clean Water Act protections for vast stretches of wetlands, proposed massive job cuts at the Environmental Protection Agency and prepared to begin revoking the Obama administration’s most ambitious climate change regulations.

Trump is also expected to overturn Barack Obama’s moratorium on new federal coal leases, and is considering automakers’ pleas for relief from a scheduled tightening of vehicle fuel-efficiency standards. Obama’s pledge to send billions of dollars to United Nations climate programs is also likely on the chopping block. And Trump hasn’t ruled out withdrawing the United States from the 200-nation Paris climate agreement, a step that could undercut the international effort to confront global warming.

Trump’s actions are true to his campaign rhetoric, including his promises to “get rid of” the EPA “in almost every form.” They thrill conservative groups like the Heritage Foundation that share his disdain for federal regulations and want Washington to give more control to the states.

But they run afoul of some of Trump’s greener post-election head fakes, including a much-publicized meeting in Trump Tower with Al Gore and media speculation that the president’s daughter Ivanka might serve as a de-facto climate czar.

Trump’s approach alarms environmental advocates and their allies in Congress, who say his early policy moves threaten to pollute the nation’s air and water while undermining the future of the planet. They would also hobble agencies like EPA: The spending cuts Trump has ordered would chop nearly 25 percent of that agency’s budget, even sharper than the reductions Ronald Reagan oversaw in his first term.

Unlike Reagan, Trump has no Democratic House majority to resist his policies. And decades after Reagan left office, scientists warn that policymakers have little time left to prevent the most catastrophic effects of climate change.

“I would call it the worst environmental disaster of all time if he has the ability to implement the plans which he has outlined,” Sen. Ed Markey (D-Mass.) said of Trump.

Even some Republicans are concerned.

“I haven’t ever really seen anything quite like this,” said Christine Todd Whitman, who served as George W. Bush’s first EPA administrator, warning that any effort to weaken enforcement of environmental rules could harm public health. “A lot of that enforcement is protecting people.”

The Environmental Defense Fund, which has for decades cultivated relationships with Republican administrations, was so concerned about Trump’s agenda that it publicly opposed Scott Pruitt’s nomination for EPA administrator, a first for the group. As Oklahoma’s attorney general, Pruitt had led legal challenges against a series of major EPA regulations, including a power plant rule that formed the centerpiece of Obama’s climate strategy.

“We’ve worked with every Democrat and every Republican, and we’ve never opposed any Cabinet official, period,” EDF President Fred Krupp said in an interview. “That’s how far outside the bipartisan environmental tradition the agenda is.

“The very bedrock protections that have led to dramatically cleaner air and a healthy environment through both Democratic and Republican administrations are under attack,” he added.

The White House did not respond to a request for comment on this story. But conservatives say it’s about time someone started cutting back Washington’s tangled environmental bureaucracy.

“In a lot of ways the federal government has bitten off more than they can chew,” said Nick Loris, an energy and environment economist at Heritage, which worked closely with Trump officials during the transition. “The Trump administration is undoing a lot of the regulations that the Obama administration put forth that would increase the cost of energy and would really be devoid of any environmental benefit.”

At the EPA, one career official said many nervous employees are living by two mantras: “Shelter in place” and “Wait and see.” The official said senior career staffers are “being kept out of the loop on major decisions” amid distrust from Trump’s political appointees.

“Some folks have zero work,” the official said. “Others, who the appointees trust because they are Republican, are getting overtime while their counterparts are dying to get work assignments.”

To some long-time environmentalists, Trump’s unabashed assault on key planks of Obama’s agenda are especially harrowing.

“Reagan, and [George W. Bush] after him, made their big moves on Friday afternoon when the media had gone home or cloaked in Frank Luntz cotton-candy phrasing so that only the intended donor beneficiaries would know what was happening,” said Carl Pope, who led the Sierra Club for nearly two decades. “Trump proclaims it in prime time. He’s not just trying to change policy. He’s trying to eliminate a key phrase in the Constitution: ‘promote the general welfare,’ by changing our public culture.”

At the EPA, some career employees privately draw comparisons between Pruitt and Anne Gorsuch Burford, who drew widespread criticism from environmentalists and Democrats while leading the agency during Reagan’s first term.

Burford — the mother of Trump’s Supreme Court nominee, Neil Gorsuch — slashed the EPA’s budget by 22 percent and once bragged that she cut the agency’s book of clean water regulations from 6 inches thick to a half-inch, according to her Washington Post obituary from 2004. Her tenure included being held in contempt by the House after Reagan ordered her not to turn over records about Superfund cleanups.

At the core of Trump’s approach to energy and environmental issues is a disdain for federal regulation and bureaucracy, paired with a desire to streamline permit approvals. That was the motive behind one of his earliest executive actions, an order commanding federal agencies to rescind two regulations for every one they enact.

Trump has also signed off on congressional repeals of some Obama-era regulations, including an Interior Department rule meant to protect streams from pollution by mountaintop removal coal mining. And this week, he ordered EPA to begin rewriting the Obama administration’s sweeping “Waters of the U.S.” rule, a move that green groups say could leave 60 percent of U.S. stream miles and 20 million acres of wetlands unprotected from development or pollution.

Next week, Trump is set to sign an executive order that will start the process of unraveling Obama’s most important climate change regulations, aimed at limiting greenhouse gas emissions from coal-burning power plants. Those rules were the centerpiece of Obama’s commitment to other nations that the U.S., the world’s second-biggest carbon polluter, would do its share to lessen the causes of global warming.

A person familiar with Trump’s order said it is expected to emphasize increasing U.S. energy independence and maximizing domestic energy production on federal lands, while eliminating and streamlining regulations. The order will also overturn the Obama administration’s 2015 moratorium on new coal leases on federal lands.

The order won’t have instant effect: It could take years for EPA to undo the regulations, and the administration will face fierce legal challenges from environmental groups.

Despite Trump’s aggressive early moves, some of his advisers are pushing a more moderate approach on environmental policy — chiefly Ivanka Trump and her husband, Jared Kushner. The couple succeeded in removing language criticizing the 2015 Paris climate deal from the president’s upcoming executive order, as The Wall Street Journal first reported.

Trump’s advisers have not yet fleshed out a detailed position on whether the U.S. should stay in the Paris agreement, according to a person close to the process. Some advisers have argued the U.S. should pull out altogether, a process that would take years under the agreement’s rules. Others favor staking out a middle ground, perhaps by staying in the agreement and rewriting the emissions reduction targets that Obama set.

In some ways, the debate is symbolic: None of the carbon reductions outlined in the Paris deal are legally binding. But climate advocates say U.S. leadership is critical to getting other nations to follow through on their pledges — so a pullout could undermine the agreement.

Trump has been equivocal on the Paris deal, saying during the campaign that he would “cancel” the agreement but later saying he has an “open mind.” Secretary of State Rex Tillerson said during his confirmation hearing that the U.S. must keep “its seat at the table” for climate talks, but he didn’t commit to staying in the agreement.

Trump’s critics and supporters alike are looking for clues about his future policy moves in his remaining personnel choices.

For example, sources close to the administration told POLITICO the administration is considering nominating Kathleen Hartnett White, a former Texas environmental regulator who is a vocal skeptic of mainstream climate science, to lead the White House Council on Environmental Quality, a move that would infuriate green groups and signal a continuation of the president’s current approach.

But sources said the White House is also considering less divisive candidates for the job. Those include Marty Hall, who was CEQ’s chief of staff during the George W. Bush administration and is now an executive at the Ohio-based electric utility FirstEnergy.

In the meantime, though, defenders of the EPA are urging Trump not to ignore the agency’s core missions, which are to protect human health and the environment.

“If EPA doesn’t provide these protections, no one else will,” said William Reilly, the EPA administrator under President George H.W. Bush. “No one else in the government has that mandate. It’s EPA or nothing.”