Environmental groups say they are suing the federal government over its decision to remove gray wolves in the upper Great Lakes region from the endangered species list.
The Center for Biological Diversity and four other groups said they were preparing Monday to file their suit in federal court in Washington.
They contend the U.S. Fish and Wildlife Service acted too hastily last month when it removed federal protections from the estimated 4,000 wolves in Michigan, Minnesota and Wisconsin.
The wildlife agency says the wolves have recovered from the brink of extinction and are capable of surviving under state management.
Opponents also sued earlier this month over the government's removal of wolves in the northern Rockies from the endangered list.