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
Oregon gunman killed himself after police shot him 1:25 p.m. US judge declines to undo government order on green cards 1:33 p.m. Seattle officer fired for obstructing investigation 1:36 p.m. Alaska hired consultants ahead of Obama visit 1:35 p.m. State ferries selling 9 generators it bought but never used 1:33 p.m. Portland to recognize Indigenous Peoples Day 1:19 p.m. Threat causes Southern Oregon University to cancel classes 1:37 p.m. EPA rushed to judgment in blocking Alaskan gold mine, report suggests 1:36 p.m.
Our new comment system is not supported in IE 7. Please upgrade your browser here.