The controversy over drilling for oil in the Atlantic Ocean has been reignited by the election of Donald Trump, and environmentalists and coastal businesses say it could be the first major fault line that divides them from the new president.

The Obama administration has moved to restrict access to offshore oil drilling leases in the Atlantic, as well as off Alaska. Commercial oil production has never happened off the East Coast — and environmentalists consider that a major victory during Obama’s tenure.

But President-elect Trump has said that he intends to use all available fuel reserves for energy self-sufficiency — and that it’s time to be opening up offshore drilling.

While supporters say that expanded oil exploration is poised to become one of Trump’s signature accomplishments, environmentalists and other opponents see oil drilling policy as a looming conflict. Jacqueline Savitz, vice president of the ocean conservationist group Oceana, said she fears a return to the hard-fought struggles environmentalists faced with the previous Republican administration.

“We’re hoping we’re not about to fall back into the ‘drill, baby, drill’ way of thinking,” she said. “Offshore drilling in the Atlantic is not a good investment.”

The American Petroleum Institute, a key voice of the oil and gas industries, has long said more aggressive drilling is needed for the U.S. to remain a world leader in energy production. The group accused Obama in May of lacking a long-term “vision” for fossil fuels extraction; its leaders say that Trump’s presidency represents a new dawn and that they intend to hold him to his word about fossil fuels.

“As a candidate, President-elect Trump pledged to pursue an energy approach that would include opening federal lands for oil and gas production including offshore areas,” said institute spokesman Michael Tadeo.

Early signs suggest Trump will make good on his plans for more aggressive drilling.

One of his favorites to lead the Environmental Protection Agency is Myron Ebell, director of the Center for Energy and Environment at the Competitive Enterprise Institute and a prominent rejecter of the scientific consensus on climate change. He is a longtime ally of the petroleum industry and a critic of the agency he would lead.

Trump’s favorites for energy secretary include Oklahoma oil billionaire Harold Hamm and drilling proponent Rep. Kevin Cramer of North Dakota.

The Trump transition team did not respond to requests for comment. Trump has said that it’s “incredible that we’re going slow on drilling,” and that he supports coastal drilling when it “can be done responsibly.”

Trump’s stance threatens to put a political promise ahead of science, said Cascade Sorte, a professor of biology with a focus on marine systems at the University of California, Irvine.

“I’m concerned there might not be the data that we need about what we’re destroying before we destroy it,” she said.

The Gulf of Mexico is the main offshore area that the U.S. plumbs for oil and gas. But in March 2010, Obama’s administration released a report that said the Gulf alone can’t be expected to meet increasing energy demands. The report included the possibility of opening up offshore Virginia for oil and gas exploration, and the administration signaled leases in the middle and southern East Coast were possible.

The plan got immediate pushback from environmental groups, who feared it would damage ecosystems. A month later, the Deepwater Horizon explosion in the Gulf of Mexico put a hold on plans for expanding drilling.

Environmentalists say any attempt to reverse Obama’s restrictions on Atlantic and Alaskan drilling would galvanize resistance, as happened after the Gulf spill — and before that, following the 1969 Santa Barbara, California, oil spill and the 1989 Exxon Valdez oil tanker disaster in Alaska.

“If President-elect Trump tries to undo any of those measures, he will be rejecting both science and the people and he will meet opposition,” said Greenpeace spokesman Perry Wheeler.

Democratic senators on both coasts have called for Obama to block any possibility of Pacific or Atlantic drilling before Trump takes office.

Many Alaska officials strongly back opening the Beaufort and Chukchi seas in the U.S. portion of the Arctic Ocean to drilling. But Obama’s administration last week announced a five-year offshore drilling plan that blocks the sale of new oil and gas drilling rights there.

The administration also has announced the Atlantic would not be included in the next round of offshore oil leases, available from 2017 to 2022. Connie Gillette, who oversees leases for the Bureau of Ocean Energy Management, said that for now, the soonest any leases could be offered is 2023 to 2028.

Among those opposed to Atlantic drilling is Rep. Mark Sanford, a South Carolina Republican, who says his opposition dovetails with the conservative value of local control, including of natural resources. He said he is waiting for Trump to settle in before engaging him on the issue.

Many coastal business owners and residents have taken stands against Atlantic drilling, saying it would endanger key industries, such as commercial fishing and tourism. Frank Knapp, a South Carolina businessman who is the co-founder of the 12,000-member Business Alliance for Protecting the Atlantic Coast, said they’ll fight any attempts to drill once Trump takes over.

“I don’t know what his personal convictions are, but I do know … a Republican Congress wants to drill every place they can, including off the Atlantic Coast, and we’re very concerned that they will push Trump to accomplish that,” he said.