The Trump administration on Wednesday announced a broad onslaught against environmental regulations, laying the groundwork to dismantle everything from air toxics limits to an Obama-era finding that underpins the agency’s climate change rules.

EPA Administrator Lee Zeldin heralded the reconsiderations of dozens of agency rules, promising the “biggest deregulatory action in U.S. history” in a video posted on social media.

Many of the regulations under review affect oil, gas and coal and the planet-warming emissions tied to burning those fuels. One target for reconsideration is the 2009 determination that greenhouse gases endanger public health and welfare — a finding that underpins existing EPA rules for power plants, automobiles and other sources.

EPA also plans to take another look at Biden-era climate rules for power plants and vehicles, a greenhouse gas reporting program and other high-profile regulations from the Obama and Biden administrations that the Trump EPA says “have suffocated nearly every single sector of the American economy.”

Also targeted is a rule published last year that significantly strengthened the annual exposure standard for the fine particles often dubbed soot that are tied to tens of thousands of premature deaths each year.

In a letter to President Donald Trump last December, the National Association of Manufacturers and dozens of other trade groups called on his incoming administration to at least partially roll back the limit as part of a broader “regulatory reset.”

Environmental advocates and other Trump critics pledged to fight the agency. Any attempt to weaken or eliminate earlier environmental rules are certain to be challenged in court, where EPA suffered repeated losses during Trump’s first term.

“This is a despicable betrayal of the American people,” Rep. Frank Pallone (D-N.J.), the top Democrat on the House Energy and Commerce Committee, said of the endangerment finding reconsideration. Reversing that finding “will have swift and catastrophic ramifications for the environment and health of all Americans,” he said as he pledged to “fight this unlawful and unjustified action tooth and nail.”

EPA’s announcement Wednesday “is only the start of the process — not the end,” said Jackie Wong, senior vice president for climate and energy at the Natural Resources Defense Council. “Before finalizing any of these actions, the law says EPA must propose its changes, justify them with science and the law, and listen to the public and respond to its concerns.”

Wong added, “NRDC’s scientists and lawyers will be there to fight back at every step of the way.”

The actions announced Wednesday go beyond regulations.

Zeldin also signaled changes to EPA’s strategy for enforcing environmental laws. He said the agency will redirect “enforcement resources to EPA’s core mission to relieve the economy of unnecessary bureaucratic burdens that drive up costs for American consumers.”

And EPA plans to overhaul the Biden administration’s “social cost of carbon,” a metric used to assess the cost of climate change. On his first day in office, Trump ordered EPA to weigh eliminating the “social cost of carbon” from regulatory decisions and to consider the legality of the “endangerment finding.”

In a show of administrationwide support for reconsidering the 2009 endangerment finding, EPA issued a press release including quotes cheering the move from OMB Director Russ Vought, Interior Secretary Doug Burgum, Energy Secretary Chris Wright and Transportation Secretary Sean Duffy, as well as Jeff Clark, who’s leading the White House Office of Information and Regulatory Affairs.

An underlying feature will be a renewed embrace of “cooperative federalism.” During the first Trump administration, that phrase was typically used as a shorthand reference for shifting regulatory power from EPA to the states.

Another rule targeted Wednesday is a Biden-era regulation mandating that utilities clean up hundreds of coal ash dump sites across the nation. The rule — now being revisited by Trump’s EPA — would force the closure of older dump sites, including some that have contaminated groundwater with toxic heavy metals.

Also under reconsideration is a Biden-era rule that requires coal power plant owners to curb wastewater pollution that flows directly into rivers, streams and lakes.

The forthcoming new regulations on coal ash will “allow states to lead the charge,” Zeldin said.

Critics say that some states have struggled to ensure coal ash dumps are properly cleaned up. Under the Biden administration, EPA made coal ash cleanup a national priority and denied Alabama’s coal ash management program, charging that it wasn’t sufficiently protective of public health.

Zeldin’s announcement offers a panoramic view of steps that in some instances are already under way. Last week, for example, EPA signaled its intention to rewrite Clean Air Act regulations issued last year that aim to bolster safeguards against potential deadly chemical accidents from thousands of refineries, water treatment works and other plants that have to file risk management plans.

EPA also announced earlier Wednesday that it would revise a major rule under the Clean Water Act, which could potentially exclude more wetlands from federal permitting and mitigation requirements. Wetlands across the nation have been facing a precipitous decline due to development, agricultural pressures and sea-level rise, the Fish and Wildlife Service warned last year.

While Zeldin’s announcement boasts of “ending” the 2023 “good neighbor” smog control plan issued by the Biden administration, EPA lawyers were considerably more circumspect in a motion filed late Tuesday that asks federal judges for the chance to revisit the plan.

That Biden-era blueprint seeks to further crack down on emissions from power plants and other industrial sources that blow downwind and undercut smog standard compliance outside of their respective states; implementation is currently on hold in the wake of a Supreme Court ruling last June.

The Trump administration now wants to reconsider key features of those regulations. At this point, however, “EPA cannot say now whether its review will reveal any error” that would require a new rule, the agency’s lawyers said in Tuesday’s motion with the U.S. Court of Appeals for the District of Columbia Circuit.

Yet to be seen is whether the court grants EPA’s request. Oral arguments in lawsuits challenging the Biden-era plan are now scheduled for April 25; a three-judge panel had previously rebuffed the agency’s bid to put proceedings on hold. One more rule singled out by Zeldin is an update to air toxics standards for coal-fired power plants published last year.

The rollbacks would help advance the Trump administration’s “energy dominance” agenda, Zeldin said in a Wall Street Journal op-ed published Wednesday. “Under President Trump’s leadership, we are recommitting to the core American values of innovation, growth, exceptionalism and opportunity,” he wrote.

Still, the exact number of regulations being amended was not immediately clear. Zeldin said he was taking 31 actions, but EPA’s list as of Wednesday afternoon only included 22 specific items.

The initial announcement is fuzzy on the administration’s tack toward the regional haze program, which aims to clear the air in the Grand Canyon and dozens of other national parks and wilderness areas by 2064.

Under Democratic presidents, EPA has repeatedly used haze-control requirements to force power plants to cut emissions or close, spurring accusations of federal overreach from Republican lawmakers and industry representatives. EPA is now in the process of reviewing a new round of long-term state cleanup plans. The announcement says only that the regional haze program is targeted for “restructuring.”

EPA didn’t provide details on how it plans to change the rules on cars and heavy-duty trucks, which were central to the Biden administration’s plan to tackle climate change and promote domestic jobs.

Trump campaigned on getting rid of what he called the “EV mandate,” saying it was hurting consumers.

“The American auto industry has been hamstrung by the crushing regulatory regime of the last administration,” Zeldin said in a news release.

EPA’s rules for cars were expected to push the auto industry to broadly electrify its fleet, although the Biden administration left room for carmakers to build hybrids and other alternatives.

It doesn’t ban internal combustion engines but sets the fleetwide standard for emissions low enough that the industry would have to build more electric and hybrid models. The final version projected that up to 56 percent of new cars sold in 2032 would be fully electric, and another 13 percent will be hybrids.

The regulation for trucks follows the same outlines. EPA projects that 17 percent of the largest truck will be fully electric, and another 15 percent will be a mix of hybrids, natural gas engines or other alternatives. The required mix of low-emissions engines is higher for smaller classes of trucks.

Both the passenger-vehicle industry and the trucking industry have argued against the rules. The Alliance for Automotive Innovation has said the rules impose high costs and are out of line with what consumers want, and the American Trucking Associations has said some of the technology, particularly for heavy-duty trucks, is unworkable. Electric vehicles are also constrained by relatively low range and a lack of public battery chargers.

The truck rule “in its current form is unachievable given the state of battery-electric technology and the sheer lack of charging infrastructure,” American Trucking Associations President Chris Spear said in a statement.

“This rule has been an albatross for the trucking industry, threatening to reduce equipment availability, increase costs for businesses and consumers, and cause major supply chain disruptions. It is critically important that the federal government set realistic standards with achievable targets and timelines,” Spear added.

At the same time, carmakers are building increasing numbers of electric vehicles in part to fend off competition from foreign rivals, particularly in China. High tariffs prevent most of those vehicles from being sold in the United States, but they’re gaining a share of the international market from Europe to Asia.

Ford CEO Jim Farley has called China’s EVs an existential threat, even as his company has slowed down plans to build more battery-powered vehicles.

That’s one of the reasons that killing the rule is short-sighted, said Dan Becker, who runs the Safe Climate Transport Campaign at the Center for Biological Diversity. In the long run, cutting the regulations on cars will hurt the carmakers and drive up pollution.

“The future of the car is electric, and any company that decides not to make electric cars is just shooting itself in the tailpipe,” he said.

Ellie Borst contributed to this report.