The Trump administration on Monday extended rollbacks of the nation’s environmental laws to the Endangered Species Act, a cardinal conservation program that’s helped keep wolves, whales and condors, among scores of other critters, flourishing across the West.

The plan put forth by the Interior Department changes the way the nearly half-century-old law is administered, potentially making it harder to win new protections for struggling plants and animals and maintain safeguards for already protected wildlife.

Interior Secretary David Bernhardt said the changes were needed to modernize the unwieldy regulatory process that landowners and industry face when pursuing new business ventures, but will still ensure “recovery of our rarest species.” Environmental groups, however, argued that the new policy would test the survival of many of the more than 1,600 plants and animals covered by the landmark law.

Already, California Attorney General Xavier Becerra has threatened to sue the federal government over the changes, while California lawmakers are reaffirming support of legislation to counter the move, at least in the Golden State. Known as the Trump Insurance Law, SB1, if passed, would empower local and state governments in California to maintain federal environmental laws in place before President Trump moved into the White House.

President Trump’s decision to roll back the #EndangeredSpeciesAct would put a nail in the coffin of the wildlife and ecosystems already in critical danger because of #climatechange.



We’re ready to defend the ESA and #protectwildlife. #StopExtinctionhttps://t.co/yB5VB1ZPMJ pic.twitter.com/MoJ7K4NrTc — Xavier Becerra (@AGBecerra) August 12, 2019

The administration’s changes to the Endangered Species Act were expected to be officially released in the Federal Register. They would take effect 30 days later, barring any reversal by the Interior Department.

The Endangered Species Act is one of the nation’s most significant pieces of environmental legislation. Providing help for flora and fauna on the brink of extinction, it was signed into law by President Nixon in 1973 and has since been credited with saving hundreds of species, including the iconic bald eagle, grizzly bear and American alligator.

In California, 134 plants and 86 animals are listed as “endangered” under the law, while 52 plants and 41 animals are considered “threatened,” meaning almost endangered. The endangered listings range from black abalone to the San Bruno elfin butterfly to delta smelt to bighorn sheep.

Under the law, any new use of land — for example, building a housing development — must not interfere with any of these listed plants or animals and prove its case before proceeding.

While the ability to change the law is reserved for Congress, the executive branch can alter the often-technical procedures with which it is implemented.

The administration’s changes put less emphasis on potential long-term threats to a plant or animal by redefining the term “foreseeable future.” Consequently, things like global warming may not be considered when looking at how to protect a given species. The amount of “critical habitat” set aside for wildlife, for example, could ultimately be less.

The plan also allows the federal government to evaluate the economic costs of wildlife protection.

In addition, the policy would make it easier to delist a species, as well as to do away with blanket protections for plants and animals that are newly designated as threatened, in favor of requiring individually prescribed preservation measures.

Environmentalists say the changes amount to a windfall for industry groups, which may have an easier time getting mining, logging, and oil and gas projects off the ground.

“These are big changes and designed to weaken protections,” said Kim Delfino, California program director for the national environmental group Defenders of Wildlife. “It’s unfortunate that this is where we are at at the federal level.”

California has its own Endangered Species Act, which covers many of the same plants and animals safeguarded by the federal law, as well as species that don’t have national protections. The problem is that the California law doesn’t cover all the species that have federal protection. Nearly 80 animals and more than 60 plants currently covered by federal regulations are without state safeguards.

The California Department of Fish and Wildlife has the power to protect more plants and animals, but the process generally takes about two years, time that could prove crucial for a some species.

Proponents of SB1, authored by state Sen. Toni Atkins, D-San Diego, say the legislation offers a much quicker solution. The proposed law essentially calls for any federal environmental rollback or worker-safety standard in place before Jan. 22, 2017, to remain in effect even if Washington does away with it.

The bill, which was approved by the Senate and is being considered by the Assembly, would expedite state protection for plants and animals not already covered by California’s Endangered Species Act.

While the move could help many fragile species in California, it would do little to assist plants and animals in other states, or those in California that may roam beyond the state border.

“It’s not like we’re an island,” said Lisa Belenky, attorney for the environmental group Center for Biological Diversity. “Wolves go into Oregon. Condors fly all over the inter-mountain West. We’re all connected.”

Becerra was joined Monday by Massachusetts Attorney General Maura Healey in committing to halt the changes to the Endangered Species Act as quickly as possible. The two said they were preparing a lawsuit that would argue that the federal move was “arbitrary and capricious,” failed to review the environmental impacts of the changes, and violated the very text of the 1973 law.

“This is not the time to go low and go slow and go backward in protecting our planet’s biodiversity,” Becerra said in a phone call with reporters.

The changes to the Endangered Species Act are among many regulatory rollbacks the Trump administration has proposed over the past two years regarding the nation’s environmental policy. The Clean Water Act and the Clean Air Act are among recent targets. California has turned to legal action in these cases as well.

Some, however, were pleased to see the administration’s move Monday. Industry groups, joined by many Republicans in Congress, have long sought to limit the purview of the Endangered Species Act, citing its restrictions to business and economic development.

“The California Farm Bureau Federation supports the changes,” said agency spokesman Dave Kranz. “Farmers and ranchers want to make the Endangered Species Act work better for species and for people who manage natural resources. We believe the regulations will benefit protected species while easing the impact on farmers and ranchers.”

In a prepared statement, U.S. Secretary of Commerce Wilbur Ross said, “The revisions finalized with this rule making fit squarely within the president’s mandate of easing the regulatory burden on the American public.”

Kurtis Alexander is a San Francisco Chronicle staff writer. Email: kalexander@sfchronicle.com Twitter: @kurtisalexander