A U.S. appeals court ruled Friday that a regulation requiring deep cuts in carbon emissions from power plants can go ahead while it considers an objection from more than two dozen Republican-led states.

The Environmental Protection Agency’s regulations apply to existing coal-fired power plants and all new natural gas plants.

The U.S. Court of Appeals for the D.C. Circuit in Washington, D.C., ruled that a stay was unnecessary because the states were not suffering immediate harm, since the earliest possible compliance deadline for the regulations is 2030.

An EPA spokesman said the agency welcomed the ruling. West Virginia Attorney General Patrick Morrisey, who is leading the challenge, said in a statement that the rule was unlawful and that he would ask the U.S. Supreme Court for a stay.

The rule, part of Democratic President Joe Biden’s broader climate agenda, requires greenhouse gas emissions to be reduced by 90% by 2032.

Not only the states of Indiana, Ohio and Kansas, but also trade associations of utilities, mining and coal industries have objected to this.

To comply, the U.S. power sector, which is responsible for nearly a quarter of U.S. greenhouse gas pollution, would have to install expensive emissions control technologies or close the most polluting coal-fired power plants.

According to the EPA, the reductions are achievable if the plants install carbon capture and storage technology that prevents emissions from entering the atmosphere.

The challengers argue that the method has not yet been meaningfully deployed and is too expensive. They have also said that the EPA exceeded its authority by making the rule and needed explicit approval from Congress to do so.