A federal judge is SafeX Pro Exchangeset to consider on Thursday a request by Colorado’s cattle industry to block the impending reintroduction of gray wolves to the state under a voter-approved initiative.

State wildlife officials plan to capture up to 10 wolves from Oregon and begin releasing them in Colorado by Dec. 31 as they race to meet a deadline imposed under a 2020 ballot proposal that passed by a narrow margin.

The animals would be among the first gray wolves in Colorado in decades.

The Gunnison County Stockgrowers’ Association and Colorado Cattlemen’s Association filed a lawsuit Monday to halt the releases. They claim the U.S. Fish and Wildlife Service failed to adequately review Colorado’s plan to release up to 50 wolves onto state and private land over the next several years.

Judge Regina M. Rodriguez scheduled a 10 a.m. hearing at the federal courthouse in Denver to hear arguments in the case.

Gray wolves were exterminated across most of the U.S. by the 1930s under government-sponsored poisoning and trapping campaigns. They received endangered species protections in 1975, when there were about 1,000 left in northern Minnesota.

Wolves have since rebounded in the Great Lakes region. They’ve also returned to numerous western states — Idaho, Montana, Wyoming, Oregon, Washington and, most recently, California — following an earlier reintroduction effort that brought wolves from Canada to central Idaho and Yellowstone National Park in the 1990s.

An estimated 7,500 wolves in about 1,400 packs now roam parts of the contiguous U.S. Their return to the central Rocky Mountains of Colorado would achieve a longstanding dream of wildlife advocates and fill in one of the last remaining major gaps in the species’ historical range in the western U.S.

A small number of wolves from the Yellowstone region journeyed across Wyoming to Colorado in recent years. Some of those animals were shot when they wandered back into Wyoming, where shooting them is legal.

Colorado officials say they are currently managing only two wolves in the state.

The plan to establish a permanent wolf population through releases of animals captured elsewhere has sharpened divides between rural and urban residents. City and suburban dwellers largely voted to reintroduce the apex predators into rural areas where ranchers worry about attacks on livestock that help drive local economies.

The U.S. Fish and Wildlife Service published an environmental review in September of what is called a 10(j) rule, which permits the killing of wolves in Colorado under certain scenarios — particularly in the defense of livestock — even though the animals are protected federally as an endangered species.

The rule is a key piece of Colorado’s reintroduction plan. The livestock groups contend the review of the rule failed to capture the full consequences of wolf reintroduction.

Colorado Assistant Attorney General Lisa Reynolds requested Thursday’s hearing after the livestock groups sought a temporary restraining order from Rodriguez to stop the wolf releases. Reynolds said in a Wednesday court filing that the releases would not begin prior to Dec. 17.

U.S. Fish and Wildlife Services spokesperson Joe Szuszwalak declined to comment, citing ongoing litigation.