A coalition of more than two dozen states and cities sued the Trump administration Tuesday over its rollback of one of President Barack Obama’s signature regulations to reduce the nation’s carbon emissions, saying the White House is seeking to prop up the coal industry and hamper future administrations from tackling climate change.

Attorneys general from 22 Democratic-led states, six cities and the District of Columbia filed the lawsuit Tuesday in the U.S. Court of Appeals for the District of Columbia Circuit. The suit argues that the Environmental Protection Agency’s replacement for an Obama-era rule intended to push the nation toward cleaner forms of energy is illegal and should be struck down.

The action, led by New York Attorney General Letitia James, argues that the Trump regulation, which was finalized in July, does not “meaningfully” reduce carbon dioxide emissions and that the EPA is negligent in its duties under the Clean Air Act.

The Obama administration’s 2015 rule set specific targets for greenhouse gas reductions for each state. The Trump administration is instead allowing state regulators to determine how electric utilities can improve the efficiency of their plants.

Citing the Clean Air Act, the nation’s main air pollution law, the attorneys general from California, Massachusetts, Michigan, Minnesota, North Carolina, Wisconsin and other states say that the EPA must require the “best system of emission reduction available” — and that the Trump administration’s rule would only nibble away at the margins of carbon emissions.

James called the Trump administration’s version an “unlawful, do-nothing” rule Tuesday.

“We are careening towards a climate disaster,” James said in a statement. “Rather than staying the course with policies aimed at fixing the problem and protecting people’s health, safety, and the environment, the Trump Administration repealed the Clean Power Plan and replaced it with this ‘Dirty Power’ rule.”

The EPA said it believes its power plant rule will withstand judicial scrutiny. “EPA worked diligently to ensure we produced a solid rule, that we believe will be upheld in the courts, unlike the previous Administration’s Clean Power Plan,” EPA spokesman Michael Abboud said in a statement.

Under the EPA’s new rule, power companies would not be forced to switch from coal. But the availability of cheaper natural gas, solar and wind energy has already prompted many power companies to close coal plants, with or without the federal government telling them to do so.

“Climate change impacts are going up, and clean energy costs are going down,” said David Doniger, a senior climate and energy policy official with the Natural Resources Defense Council. “The EPA should be strengthening the Clean Power Plan, not replacing it.”

Doniger said the NRDC is among a coalition of environmental groups that plans to sue the Trump administration Wednesday, on much the same grounds as the attorneys general. He said he feels optimistic that the courts will recognize that the administration’s approach is an abdication of the EPA’s responsibility.

“We think that this will get struck down and EPA will be told to go do its job under the Clean Air Act, which is to protect us,” he said. “The whole purpose of having the Clean Air Act is that when you have dangerous pollution, to have government take action beyond what the market will do itself. That’s the whole point.”

The other states participating in the lawsuit are Colorado, Connecticut, Delaware, Hawaii, Maine, Illinois, Maryland, New Jersey, New Mexico, Oregon, Pennsylvania, Rhode Island, Vermont, Virginia and Washington. The cites suing include Chicago, Los Angeles, New York and Philadelphia, as well as Boulder, Colo., and South Miami, Fla.

The litigation represents a reversal from four years ago, when a group of Republican states sued to stop the Clean Power Plan from being put into effect. They accused the Obama EPA of overstepping its legal authority under the Clean Air Act and of unfairly trying to force the closure of coal-fired power plants.

One of the people leading that charge was then-Oklahoma Attorney General Scott Pruitt, who boasted of being “a leading advocate against the EPA’s activist agenda.” He would soon find himself leading the agency after President Trump’s election.

The 2015 lawsuit kicked off a strange legal fate for the Clean Power Plan.

In early 2016, the Supreme Court blocked the regulation’s implementation after a last-minute plea from 27 states and a host of other opponents that challenged its legality. The 5-to-4 decision, which did not address the merits of the lawsuit, came just days before the sudden death of Justice Antonin Scalia.

With the Clean Power Plan’s future on the line, a 10-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit in September 2016 held a marathon day of oral arguments, trying to determine whether the Obama proposal went too far in attempting to force power plants to cut carbon-dioxide emissions.

But the court did not issue a ruling before the Trump administration took office and requested time to reconsider the Clean Power Plan’s future.

In October 2017, in front of a crowd of coal miners in Kentucky, Pruitt announced that the EPA would move to repeal the Clean Power Plan and replace it with what he called a less-onerous alternative.

“The war against coal is over,” he proclaimed at the time.

The new case, filed in the U.S. Court of Appeals for the D.C. Circuit, could wind its way to the Supreme Court should Trump win a second term and stop a Democratic rival from repealing his rule before it reaches the high court.

Jeff Holmstead, a partner at Bracewell who headed the EPA’s office of air and radiation under President George W. Bush, said the Supreme Court could bring clarity to the question of how much authority the EPA has to limit carbon emissions.

“From a public policy perspective, we should hope that this case goes to the Supreme Court — so that everyone who cares about climate change will know the limits of what EPA can do under current law to reduce industrial CO2 emissions,” Holmstead said.

But Michael Gerrard, director of the Sabin Center for Climate Change Law at Columbia Law School, thought a future Democratic administration will still have room to issue stronger climate rules.

“I don’t think this new rule would limit a future administration’s options; EPA can repeal old rules and issue new ones if it has good and legal reasons,” Gerrard said. “But this whole process takes a great deal of time and impedes the momentum we need to seriously address the climate crisis.”