MONTPELIER, Vt. (AP) – The National Wildlife Federation and four other groups went to court Thursday to try to force the federal government to revive plans to restore wolves to the Northeast.

The lawsuit, filed in U.S. District Court in Burlington, charges that the Interior Department violated the Endangered Species Act last spring when it changed the classification of wolves in the continental United States from endangered to threatened.

The move by the U.S. Fish and Wildlife Service came after programs in the Rocky Mountains and upper Great Lakes states helped restore wolf populations there. Although wolves once lived in the Northeast, a program wasn’t implemented for the region.

“Although the thriving wolf populations in the Great Lakes and Northern Rockies are indeed wildlife success stories, they cannot be used as an excuse for abandoning the goal of wolf recovery in the Northeast,” said Eric Palola, director of National Wildlife Federation’s Montpelier office.

Federal officials have said the goal of the Endangered Species Act, the creation of a self-sustaining wolf population in the wild, has been met.

Wolves used to roam across much of North America, but they were pushed out of the Northeast in the late 1800s. Now there are no known wolf populations living in the Northeast, although there are wolves living in eastern Canada near the U.S. border, and individual wolves have been found in Maine.

There are tens of thousands of acres of suitable wolf habitat in areas of Maine, New Hampshire and the Adirondack mountains of New York as well as corridors through Vermont.