Facing mounting pressure from legislators over grey wolves, wildlife advocates reached an agreement with the Obama administration Friday to lift protections for the species in Montana and Idaho and allow hunting.

The settlement agreement — opposed by some environmentalists — is intended to resolve years of litigation that has kept wolves in the Northern Rockies shielded by the Endangered Species Act even as the population expanded dramatically.

It also is meant to pre-empt action by Congress, where western Republicans are leading efforts to strip wolves of their protections across the U.S.

"For too long, wolf management in this country has been caught up in controversy and litigation instead of rooted in science, where it belongs. This proposed settlement provides a path forward," said Deputy Interior Secretary David Hayes.

Court documents detailing the proposed agreement between the U.S. Department of Interior and 10 conservation groups were filed Friday in U.S. District Court in Montana.

If approved by a federal judge, the deal would keep the species on the endangered list at least temporarily in four states where they are considered most vulnerable: Wyoming, Oregon, Washington and Utah.

And it calls for the U.S. Fish and Wildlife Service to set up a scientific panel to re-examine wolf recovery goals calling for a minimum 300 wolves in the region — a population size wildlife advocates criticize as inadequate. Supporters of the settlement hope that process will accelerate wolf recovery efforts in Washington and Oregon, where populations are just beginning to take hold.

Population exterminated, then re-established

Wolves last century were exterminated across most of the lower 48 states. By the end of 2010, there were an estimated 1,651 wolves in the Northern Rockies following a 15-year, $30 million federal restoration effort.

A grey wolf watches biologists in Yellowstone National Park. (U.S. Fish and Wildlife Service, William Campbell, File/AP)

That program has stirred deep antipathy toward the predators among western ranchers and hunters, who are angry over livestock attacks and a recent decline in some elk herds.

Court rulings blocked prior efforts by the Bush and Obama administrations to lift protections for the species.

With Congress now threatening to intervene, the 10 national and local groups involved in Friday's settlement said they wanted to head off what they regard as precedent-setting legislation. They fear pending bills to delist wolves would broadly undermine the Endangered Species Act, with ramifications for imperiled fish, animals and plants across the U.S.

"Both the Fish and Wildlife Service and ourselves were in the middle of a political firestorm that all parties wanted to resolve," said Kieran Suckling of the Center for Biological Diversity, which signed on to the settlement. "The nature of a settlement is you can't get everything you want."

Four groups that had been co-plaintiffs in the case did not agree to the settlement. That will complicate efforts to garner approval from U.S. District Judge Donald Molloy in Missoula.

Attorneys for Earthjustice previously represented most of the plaintiffs in the case. They withdrew this week citing "ethical obligations," but three of the four groups opposed to Friday's agreement already have brought on new attorneys.

Western Watersheds Project executive director John Marvel said the groups that agreed to the settlement "should be ashamed" to give up the fight on wolves in the face of threats from Congress.

"What we've seen is a series of politically motivated decisions that have clearly violated the law in order to achieve a political end, and this proposed settlement is no different than that," he said, adding that his group will ask Molloy to reject the deal.

Support from Molloy is crucial. He is being asked essentially to reverse a ruling he issued last summer that reinstated wolf protections in Idaho and Montana.

Molloy is slated to become a senior judge in August, meaning another judge eventually would be appointed to take over his duties. But his office said Friday he will continue to carry a full caseload for now.

Some Republican legislators dismissed the settlement as insufficient. Wyoming Representative Cynthia Lummis, whose state was carved out of the deal, referred to it as "a wolf in sheep's clothing" and said there was no guarantee the lawsuits would stop.

In Montana, Gov. Brian Schweitzer said wolf hunting could begin as soon as this fall if the settlement holds.

Schweitzer last month had encouraged Montana residents to shoot wolves illegally if they attack livestock. He also said state officials were going to start eliminating any packs involved in such attacks — a prospect that wildlife officials warned could drive the population to unsustainable levels.

He said Friday the comments were meant to "nudge" the issue toward a settlement.

"Sometimes you get the crosshairs of the scope on something and it gets attention," he said.

Almost 1,300 wolves were tallied in Montana and Idaho in recent counts by state, federal and tribal biologists. The population reached the original federal recovery goal a decade ago but many of the groups involved in Friday's settlement had long maintained that those goals were too modest.