This story was updated Oct. 26 with the U.S. House voting.

Republicans in Congress have spent decades trying—and failing—to bring oil and gas development to one of the United States’ last truly untouched areas. Now, they appear to have the votes to make it happen.

The Arctic National Wildlife Refuge represents the final frontier of American wilderness. Its 19.3 million acres in Alaska are home to polar bears, caribou and thousands of bird species, and it is sacred to the Gwich’in people. Along its northern edge is a controversial swath of land called the coastal plain, and this is where the GOP has long fought to bring drilling.

This latest attempt to open the wildlife refuge to drilling began as the House and Senate rolled out their 2018 budget plans. In late September, the Senate Budget Committee released a proposal that includes instructions to senators who oversee energy and natural resources to find $1 billion in new revenue. It was a thinly veiled suggestion to allow drilling leases in the wildlife refuge, as Alaska Sen. Lisa Murkowski, a Republican, confirmed on Thursday.

“It is not the only option, but I will tell you that it is the best option, and it is on the table,” Murkowski said on the Senate floor.

Three Senate Democrats—Maria Cantwell (D-Wash.), Edward Markey (D-Mass.) and Michael Bennet (D-Colo.)—tried on Thursday to remove the refuge drilling plan from the budget bill, but their amendment failed, 48 to 52. Sen. Susan Collins of Maine was the only Republican to join the ranks of Democrats who supported the amendment; Democrat Joe Manchin of West Virginia voted against the measure.

“Republicans are trying to use the budget process to ram through drilling in the crown jewel of America’s Wildlife Refuge System because they know they don’t have the votes to do so through regular order,” Markey said in a statement after the vote. “Republicans are moving forward with a budget that includes this poison pill to hand over the wildest place left in America to Big Oil. This is nothing more than fossil fuel folly.”

Drilling in the refuge is not yet a done deal. The Senate Energy and Natural Resource Committee, which Murkowski chairs, will have to come up with a recommendation to meet the budget instruction. (When Murkowski joined the Senate in 2002, she picked up the mantle of fighting for drilling in the Arctic National Wildlife Refuge from her father, former Sen. Frank Murkowski, who had been fighting for it since 1980.) Because that recommendation will be voted on through the budget process, it will need only a simple majority to pass. 

On the House side, a similar instruction attached to a budget bill asks the House Natural Resources Committee to find $5 billion in federal revenue. The budget bill passed on Oct. 26, and the two chambers will now have to negotiate a final number.

“This is and always has been largely a political issue, and not an economic one,” said David Hayes, who was the Interior Department’s deputy secretary and chief operating officer at points in the Clinton and Obama administrations.

“It’s being framed as a budget amendment that could potentially yield a billion dollars in revenue for the federal government. That’s fantasy. There’s no basis for that at all,” Hayes said. “But folks who don’t appreciate the economics are potentially drawn to that.”

Not the First Attempt to Open ANWR

The coastal plain—an area roughly the size of Delaware—lacks the federal “wilderness area” designation and could, with Congressional approval, be opened for drilling.

Congressional Republicans came close in 1995, when a provision recommending opening the Arctic National Wildlife Refuge (ANWR) made it through Congress before being vetoed by President Bill Clinton. Ten years later, a similar effort gained support in the Senate but ultimately failed.

Now, with a Republican Congress, a president who supports increased fossil fuel development in the Arctic and a potential route to passage that requires just a simple majority vote, ANWR may be more vulnerable than ever before.

“It’s gotten close before, but to date, the strong public recognition that this is not a place for oil drilling has prevailed,” said Hayes, who is now the director of the State Energy & Environmental Impact Center at NYU School of Law. “But one can’t count on anything these days.”

Turning the ‘Crown Jewels’ Over to Polluters

In 2005, the effort to keep drilling out of the refuge was also led by Sen. Cantwell. In a press conference earlier this week, Cantwell pointed out that previous efforts have also relied on legislative processes that tie ANWR to other bills. “It tells you something that this idea does not stand on its own,” she said.

“I hope that we’ll all fight very hard to make sure that, on our watch, we do not give up one of the crown jewels of the United States of America,” Cantwell said. “We will resist their unbelievable attempts to turn public lands over to polluters.”

Earlier on Thursday, more than 300 businesses and organizations from across the country sent a letter to Congress asking them to protect ANWR from drilling.

“We represent a broad and diverse constituency voice that proves that folks across this country deeply appreciate our nation’s wild spaces,” the letter says. “We urge you to continue to do all you can to enact the strongest possible protections for the Arctic landscape, its wildlife and its people.”