WASHINGTON (AP) — The Supreme Court agreed on Friday to step into a fight over plans to store nuclear waste at sites in rural Texas and New Mexico.

The justices said they will review a ruling by the 5th U.S. Circuit Court of Appeals that found that the Nuclear Regulatory Commission exceeded its authority under federal law in granting a license to a private company to store spent nuclear fuel at a dump in West Texas for 40 years. The outcome of the case will affect plans for a similar facility in New Mexico.

Political leaders in both states oppose the facilities.

Republican Gov. Greg Abbott of Texas has said his state “will not become America’s nuclear waste dumping ground.”

The push for temporary storage sites is part of the complicated politics of the nation’s so far futile quest for a permanent underground storage facility.

Roughly 100,000 tons (90,000 metric tons) of spent fuel, some of it dating from the 1980s, is piling up at current and former nuclear plant sites nationwide and growing by more than 2,000 tons a year. The waste was meant to be kept there temporarily before being deposited deep underground.

A plan to build a national storage facility northwest of Las Vegas at Yucca Mountain has been mothballed because of staunch opposition from most Nevada residents and officials.

The fight over storing nuclear waste is among 13 cases the justices added to their agenda for the term that begins Monday. Other notable cases include a plea by gun makers to end a lawsuit in which Mexico seeks to blame them for gun violence south of the border and an appeal from a death row inmate in Texas whose execution the high court halted at the last minute in July.

In the NRC case, there are two issues before the justices, which will be argued early next year.

The NRC contends that the states forfeited their right to object to the licensing decisions because they declined to join in the commission’s proceedings.

Two other federal appeals courts, in Denver and Washington, that weighed the same issue ruled for the agency. Only the 5th Circuit allowed the cases to proceed.

The second issue is whether federal law allows the commission to license temporary storage sites. Texas and environmental groups, unlikely allies, both relied on a 2022 Supreme Court decision that held that Congress must act with specificity when it wants to give an agency the authority to regulate on an issue of major national significance.

In ruling for Texas, the 5th Circuit agreed that what to do with the nation’s nuclear waste is the sort of “major question” that Congress must speak to directly.

The Biden administration told the court that the commission has long-standing authority reaching back to the 1954 Atomic Energy Act to deal with nuclear waste.

The NRC granted the Texas license to Interim Storage Partners LLC for a facility that could take up to 5,000 metric tons of spent nuclear fuel rods from power plants and 231 million tons of other radioactive waste. The facility would be built next to an existing dump site in Andrews County for low-level waste such as protective clothing and other material that has been exposed to radioactivity. The Andrews County site is about 350 miles (563.27 kilometers) west of Dallas, near the Texas-New Mexico state line.

New Mexico officials, led by Democratic Gov. Michelle Lujan Grisham, are opposed to a license the commission granted to Holtec International for a similar temporary storage site in Lea County, in the southeastern part of the state near Carlsbad. The 5th Circuit also has blocked that license.

A decision is expected by the middle of next year.