The Greater Yellowstone Coalition filed a lawsuit Wednesday challenging the removal of gray wolves from Endangered Species Act protection in Idaho and Montana.

The lawsuit, filed in Montana, is separate from a suit Earthjustice attorneys filed earlier this month for 12 groups, including the Jackson Hole Conservation Alliance and the Natural Resources Defense Council. The state of Wyoming and some livestock and sportsmen groups followed with a lawsuit in Wyoming.

While Greater Yellowstone Coalition officials say they support eventual state management of wolves once adequate standards and safeguards are in place, they say the delisting fails to ensure thriving populations in the northern Rockies and undermines efforts to find sound, science-based solutions to wolf-management issues. Further, the group says delisting lifts wolf protection before achieving the necessary level of connectivity between populations in the Greater Yellowstone Ecosystem and central Idaho. The group also faults Idaho’s aggressive plans to reduce its wolf population.

“Wolf reintroduction has been a remarkable success story in so many ways, and we want to see the three states manage wolves in Greater Yellowstone eventually, but this delisting plan is a giant step backward,” said Craig Kenworthy, the Greater Yellowstone Coalition’s conservation director. “Unfortunately, the Interior Department and the states have yet to produce plans that adequately address the long-term viability of wolves in the region.”

Delisting of wolves in Idaho and Montana became official May 4. Wolves remain protected under the Endangered Species Act in Wyoming because the U.S. Fish and Wildlife Service has not accepted the state’s management plan.