In a court filing Monday, government attorneys say "a recent unexpected delay" is indefinitely holding up action on the predators. No further explanation was offered.
Gray wolves are under protection as an endangered species and have recovered dramatically from widespread extermination in recent decades.
More than 6,000 of the animals now roam the continental U.S. Most live in the Northern Rockies and western Great Lakes, where protections already have been lifted.
A draft proposal to lift protections elsewhere drew strong objections when it was revealed last month.
Wildlife advocates and some members of Congress argue that the wolf's recovery is incomplete because the animal occupies just a fraction of its historical range.
More Northwest Headlines
Highway 20 reopens as North Cascades wildfire danger eases Rain and rising humidity help firefighters Man struck, killed by Amtrak train in Tacoma Washington budget writer leaving House to run Early Learning Man extradited from Mexico to be arraigned for Bellevue rape Department of Transportation to widen I-5 near JBLM Last of 3 candidates visiting WSU Crab fishing resumes on north coast of Washington
Our new comment system is not supported in IE 7. Please upgrade your browser here.