BILLINGS, Mont. (AP) — The Obama administration is taking steps to extend new federal protections to a list of imperiled animals and plants that reads like a manifest for Noah's Ark — from the melodic golden-winged warbler and slow-moving gopher tortoise, to the slimy American eel and tiny Texas kangaroo rat.Compelled by a pair of recent legal settlements, the effort in part targets species that have been mired in bureaucratic limbo even as they inch toward potential extinction. With a Friday deadline to act on more than 700 pending cases, the U.S. Fish and Wildlife Service already has issued decisions advancing more than 500 species toward potential new protections under the Endangered Species Act.Observers said the agency's actions mark a breakthrough for a program long criticized by conservatives and liberals alike as cumbersome and slow. But most of the decisions made under the new settlements are preliminary, and key Republicans vowed Thursday to press forward with their plans to put the brakes on a law they blame for jeopardizing economic growth.Still, said Patrick Parenteau, an environmental law professor at the Vermont Law School, "Here at a single glance, you see the sweep of the Endangered Species Act. They are moving through this large backlog at a fairly crisp clip now. This is the largest number of listing actions we've seen in a very long time, in decades."Decisions on about 60 more species covered under the settlements are expected Friday, the Fish and Wildlife Service said.The flurry of action could help revive President Barack Obama's standing among wildlife advocates upset over the administration's support for taking gray wolves off the endangered list in the Northern Rockies and Upper Great Lakes, among other issues.It also could set the stage for a new round of disputes pitting conservation against development. In the Southeast, for example, water supplies already stretched thin could be further limited by constraints resulting from a host of new fish, salamanders, turtles and other aquatic creatures eligible for protections.In response to the administration's decisions under the settlements, Republicans including U.S. Rep. Doc Hastings, chairman of the House Natural Resources Committee, repeated their call to overhaul the 37-year-old endangered act. The Washington state lawmaker is planning hearings this fall into what he characterizes as the law's failure."The ESA is unfortunately now used as a tool in costly lawsuits where politics trump science and jobs and economic prosperity are put in jeopardy," Hastings said Thursday.Earlier this year, citing restrictions against development and other activities, GOP lawmakers unsuccessfully sought to strip the federal budget of money to list new species as threatened or endangered. The administration is seeking $25 million for the listing program in 2012, an 11 percent increase.No projections were available for how much it would cost if hundreds more species were listed as threatened or endangered.For those already listed, a 2006 study from the Government Accountability Office found projected recovery costs ranged widely — from $125 million for the whooping crane, to $58,000 for the decurrent false aster, a type of flower. The GAO pegged the average cost for the species it examined at $15.9 million, with recoveries often lasting decades.Determining the broader costs to the economy is more difficult. Lost jobs from restrictions placed on logging or agriculture might be offset by benefits to outdoor recreational industries like boating or fishing, said Jason Shogren, a natural resources professor in the economics department at the University of Wyoming.Under the current settlements, only 13 new animals and plants have reached the final step and been added to the almost 1,400 species on the government's threatened and endangered list. Also, not every species made the cut to take the next step. Roughly 40 rejections have been meted out, including for plains bison, the giant Palouse earthworm of Idaho and Utah's Gila monster. Those rejections are subject to court challenges.Among species that advanced for further consideration are 35 snails from Nevada's Great Basin, 82 crawfish from the Southeast, 99 Hawaiian plants and a motley cast of butterflies, birds, fish, beetles, frogs, lizards, mussels and more from every corner of the country.Some have languished for decades on a "candidate list" of species the government says warrant protection but that it lacks the resources to help.That deadline was established in a pair of settlements approved by U.S. District Judge Emmet Sullivan on Sept. 9. Those deals resolved multiple lawsuits brought against the Fish and Wildlife Service by Arizona-based Center for Biological Diversity and New Mexico-based WildEarth Guardians.WildEarth Guardians' Mark Salvo said the agency's actions so far lend credence to claims that the affected species were in serious trouble."The science supports protecting these species," he said.Fish and Wildlife Service director Dan Ashe praised the deal in a statement, referring to the Endangered Species Act as a "critical safety net for America's imperiled fish, wildlife and plants."Agency spokeswoman Vanessa Kauffman said much of the work to comply with the settlements was well under way before the deals were finalized. The settlements also contained provisions to limit the number of petitions that can be filed by the two environmental groups if they want more animals and plants considered for protections.Kauffman said that would free up agency staff to spend more time on species recovery.Noah Greenwald with the Center for Biological Diversity said the Fish and Wildlife Service was making "substantial progress.""This is what we were looking for — starting to move species out of the pipeline into listing, and getting more species into the pipeline to get them under consideration," he said.Under the settlements, the Fish and Wildlife Service put off decisions on some of the more contentious species, including greater sage grouse, the Pacific walrus and Sonoran desert tortoise. Those are due over the next several years and could have wide-ranging implications for oil and gas drilling, grazing and, in the case of the walrus, potentially for climate change policies.Similar tensions have surfaced throughout the Endangered Species Act's history, from fights in the 1990s over the spotted owl and logging in the Pacific Northwest to recent clashes over how much undeveloped habitat threatened grizzly bears need.But there are ways to work through those conflicts, said Thomas Lovejoy, with the Heinz Center in Washington. A former biodiversity adviser to the World Bank, Lovejoy pointed to the red-cockaded woodpecker, found in 11 southern and south-central states, and said recovery was being achieved even as development continues, under deals ensuring enough habitat is protected elsewhere."The first thing that will happen is people will look at this and say, 'Oh my God, the slender salamander, what is that going to do for us?'" Lovejoy said. "It's not in every example the government tightens the screws."