Indiana, Ohio and West Virginia are seeking an emergency U.S. Supreme Court order to block the U.S. Environmental Protection Agency’s plan to reduce air pollution while they mount a court challenge.

The states and two sets of industry groups say the EPA’s recent “Good Neighbor Plan” to improve air quality across 23 states violates administrative law and represents illegal overreach by federal regulators. A three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit voted 2-1 to refuse to “stay” the EPA plan pending court review, saying the challengers “have not satisfied the stringent requirements” for such early relief in the case.