A group of 13 environmental groups on Wednesday announced plans to challenge the federal government's plan to remove wolves in the Northern Rockies from protection under the Endangered Species Act.

The Department of Interior published its wolf delisting rule in the Federal Register on Wednesday, prompting the announcement to file a 60-day notice of intent to sue.

Montana and federal wildlife officials expected a legal challenge because the same groups have sued in the past to stop delisting.

A Bush administration move to delist wolves in January initially was suspended by the Obama administration.

But just weeks later, Interior Secretary Ken Salazar decided to proceed with the same plan, which involves delisting wolves in Idaho and Montana but not in Wyoming because that state's wolf management plans are not considered acceptable for sustaining a wolf population.

The pending litigation will focus on the division of the Northern Rockies wolf population.

"Due to inadequacy of the state of Wyoming's management plan, wolves will retain legal protections in that state while becoming subjects of hunts in Idaho and Montana," the environmental coalition states in a press release. "This move is in clear opposition to long-standing Department of Interior policy, which found that wolves in the Northern Rockies constitute a single population and could not be broken up on a state-by-state basis."

U.S. Fish and Wildlife Service officials are confident that the delisting rule will hold up in court, largely because wolf numbers in Montana and Idaho have exceeded recovery goals every year since 2002.

Montana plans to be involved in defending delisting. State government likely will be directed to do so by a legislative resolution that passed the Senate on a 48-0 vote and on Tuesday cleared the House on a 90-9 vote.

The Earthjustice legal firm will pursue the case on behalf of the Natural Resource Defense Council, Defenders of Wildlife, the Sierra Club, the Center for Biological Diversity, the Humane Society of the United States, the Jackson Hole Conservation Alliance, Friends of the Clearwater, Alliance for the Wild Rockies, Oregon Wild, Cascadia Wildlands Project, Western Watersheds Project and Wildlands Project.

Jenny Harbine, an Earthjustice attorney, said Wednesday that it hasn't been determined whether the lawsuit will be filed in U.S. District Court in Missoula, as past wolf litigation has been.

"Of course, Judge [Donald] Molloy and the district court in Montana is intimately familiar with the administrative record on this case. But that decision hasn't been made at this point," Harbine said.

"We know we're going to be in litigation over this whole thing," said Ed Bangs, wolf recovery coordinator with the U.S. Fish and Wildlife Service in Montana.

There are about 1,645 wolves in the northern Rockies, Bangs said, including more than 300 in Wyoming, nearly 500 in Montana and about 850 in Idaho.

Reporter Jim Mann may be reached at 758-4407 or by e-mail at jmann@dailyinterlake.com