CHEYENNE, Wyo. - Western environmental groups say they're alarmed that the U.S. Fish and Wildlife Service is considering a plan to end federal protections for gray wolves in vast areas where the animals no longer exist.

The groups say ending federal protections would keep wolves from expanding their range back into states that could support them, including Colorado and California.

"As a matter of principle, I just think it's wrong," said Jay Tutchton, a Colorado lawyer with the group WildEarth Guardians.

Tutchton's group has sued over recent action to end federal protections for wolves in Wyoming. Wolves in most of the "Cowboy State" are classified as unprotected predators and scores have been killed since federal protections ended last fall.

"The Endangered Species Act was designed to protect species, including in places where they no longer reside," Tutchton said. "You were supposed to try to recover them, not throw in the towel."

The Fish and Wildlife Service could announce as soon as this spring whether it will propose a blanket delisting of wolves in most of the lower 48 states. Wolves in the Northern Rockies and around the Great Lakes, where reintroduced populations are well-established, are already off the Endangered Species List.

Chris Tollefson, spokesman for the U.S. Fish and Wildlife Service in Washington, DC, said Tuesday that the agency hasn't made any decision yet whether it will propose the blanket delisting. An agency report last year proposed dropping wolves from the endangered list in most areas where they're known not to live.

Even if the Fish and Wildlife Service ends federal protections, Tollefson said states would be free to cultivate their own wolf populations. "It's fair to say that there wouldn't be a prohibition, it would simply be left to the states to determine how to manage wolves in their boundaries," he said.

Tollefson said his agency regards the wolf recovery efforts in the Great Lakes states and Northern Rockies as enormous successes.

"Our view, and that of the biological community is that those populations are thriving and no longer require the protections of the Endangered Species Act," Tollefson said. "Obviously, we'll be discussing other areas as we move forward on that."

The prospect of the national delisting has prompted members of Congress on both sides of the issue to lobby the Fish and Wildlife Service Director Dan Ashe.

Seventy-two members of Congress, most of them Republicans, signed the most recent letter to Ashe on Friday urging him to go through with the delisting. Another group of scores of congressmen wrote to Ashe earlier this month urging him to reject the delisting idea.

"Unmanaged wolves are devastating to livestock and indigenous wildlife," the members of Congress, led by Rep. Cynthia Lummis, R-Wyo., and Sen. Orrin Hatch, R-Utah, and others, wrote to Ashe last week. "Currently state wildlife officials have their hands tied any time wolves are involved."

Lummis said Tuesday that the letter was intended to celebrate the successful recovery of wolves.

"I know some will wring their hands over a delisting, but for the life of me I don't understand why they don't throw a party instead," Lummis stated. "In most suitable habitat, and in states that strongly objected to their presence initially, the wolf is here to stay. For some that is a bitter pill to swallow, for others it's not enough, but the bottom line is there are wolves where there once were none, and everyone but the most litigious among us seem ready to move on."

Bob Brister, wildlife campaign coordinator for the Utah Environmental Congress in Salt Lake City, has been campaigning to restore wolves to Utah, where he said they were extirpated in the 1930s.

Brister said the effect of delisting wolves in Utah and elsewhere where they currently don't exist would be to preclude their ultimate recovery back into their historic range. He noted that wolves are hunted heavily in the Wyoming, Utah and Montana and that states can't be counted on to provide the protections new populations would need to survive.

"It's especially dire here in Utah, because we depend on wolves migrating from Wyoming and Idaho to restore wolves here in Utah," Brister said. "And when they're being hunted so intensely in Wyoming and Idaho, it greatly decreases the possibility of wolves migrating into Utah."

Erik Molvar executive director of the Bioldiversity Conservation Alliance in Laramie, Wyo., also noted that Wyoming, Idaho and Montana allow substantial wolf hunting. He said delisting wolves across the rest of the Lower 48, "would seem to be a very unwise move, given the tenuous status of wolf populations in this area."

Molvar, whose group also is challenging the recent delisting of wolves in Wyoming, said it's clear there are other areas of the West that could support wolf populations.

"It certainly is true that there are places in Colorado, particularly Rocky Mountain National Park, where elk are so overpopulated that they're becoming a nuisance, that wolves are one of the few options to restore the natural balance," Molvar said.

Tutchton said his group and others are likely to fight the sweeping delisting effort.

"I'm very sure that if wolves were delisted in Colorado, we would want to sue. If wolves get delisted in Oklahoma, I don't know. That might be a different question," Tutchton said. "There are some places where wolves would be quite viable."