Attorneys for the Fish and Wildlife Service asked U.S. District Judge Donald Molloy in Missoula to vacate the agency's February finding that more than 1,400 wolves in the region no longer needed federal protection.
The government's request Monday follows a July injunction in which Molloy had blocked plans for public wolf hunts this fall in Montana, Wyoming and Idaho pending resolution of a lawsuit by environmentalists.
"What we want to do is look at this more thoroughly," Fish and Wildlife spokeswoman Sharon Rose said. "We definitely have a lot of wolves out there, but we need to address some of (Molloy's) concerns in a way that people feel comfortable with."
At issue is whether a decade-long wolf restoration program has reversed the near-extermination of wolves, or if - as environmentalists claim - their long-term survival remains in doubt due to proposed hunting.
"This hit everybody really cold," said John Bloomquist, an attorney for the Montana Stockgrowers Association. "All of a sudden the federal defendants are going in the other direction."
The government's request to remand, or reconsider, the issue was filed in response to an April lawsuit from a dozen environmental and animal rights groups.
"I would call that victory. What they're requesting is to go back to the drawing boards," said Doug Honnold, an Earthjustice attorney representing the plaintiffs. They include the Sierra Club, Defenders of Wildlife, the Humane Society of the United States and other local and national groups.
If Molloy goes along with the government's request, the Fish and Wildlife Service would embark on a re-evaluation of wolves that could last for months or even years. The agency would again open the issue to public comment before returning with a new decision.
In the meantime, the killing of some wolves by government wildlife agents or ranchers would continue. More than 180 wolves were killed last year in response to wolf attacks on livestock.
A recent inventory of wolf populations in the three states showed their population in decline this year for the first time in more than a decade. Federal biologists say the decline occurred because wolves had filled up the best habitat in the region.
Honnold questioned whether disease, illegal hunting or other factors might have contributed to the drop, which saw wolf numbers decline from 1,545 during the summer of 2007 to 1,455 this summer.
Under the federal rule that took the animal off the list in February, authority over the region's wolf populations had passed to state agencies in Montana, Wyoming and Idaho.
In his July injunction, Molloy put that authority back in federal hands. The judge questioned whether wildlife laws within the three states - particularly Wyoming - would be enough to protect wolves from excessive or indiscriminate hunting.
Molloy also questioned whether packs had been intermingling enough to avoid inbreeding - a concern raised by recent research into wolf genetics.