SALMON, Idaho (Reuters) - The government would have until 2018 to decide whether to extend Endangered Species Act protections to hundreds of imperiled animals and plants under a deal with environmentalists submitted on Tuesday for approval by a federal judge.

The agreement between the Arizona-based Center for Biological Diversity and the U.S. Fish and Wildlife Service would settle that group's legal claims that the government has been too slow in assigning federal safeguards to various species on the brink of extinction.

The proposal, filed in U.S. District Court in Washington, D.C., must be approved by a judge.

Under the plan, the government would be required to make at least preliminary decisions by 2018 on whether to set aside critical habitat or provide other protections for more than 750 species, including the American wolverine, a bear-like animal of the mountain West, and the Pacific walrus.

"This is a landmark agreement that gives species a fighting chance to stave off extinction and survive for generations to come," said Noah Greenwald, the center's endangered species director.

The proposed deal came after negotiations between the group and the government over timelines for evaluating creatures ranging from the Florida sandhill crane to the Arkansas darter, a fish of the central Plains.

The settlement would address a backlog of 250 animals and plants the government says warrant protections but which have been placed on a waiting list behind species deemed a higher priority.

Some mammals, birds and fish have been on the so-called candidate list for decades. The deal would require those animals be approved or denied listing as threatened or endangered by the 2018 deadline.

Fish and Wildlife Service Director Dan Ashe said in a statement that the agreement would pave the way for government scientists "to more effectively focus our efforts on providing the benefits of the Endangered Species Act to those imperiled species most in need of protection."

(Editing by Steve Gorman and Peter Bohan)

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