Senate Democrats on Thursday criticized legislation introduced by their Republican counterparts that would open a portion of the Arctic National Wildlife Refuge to oil and natural gas drilling, but acknowledged there is little they can do to stop it.

Democrats have long been successful in blocking Republican efforts to allow energy exploration in a 1.5 million-acre section of the 19.6-million-acre Alaskan refuge in ANWR, known as the “1002 area,” where billions of barrels of crude oil lie beneath the coastal plain.

But this year, GOP control of Congress means the bill is being considered under budget reconciliation, meaning it is not subject to a Senate filibuster and can pass with a simple majority.

“We don't think this has been a fair and open process,” said Sen. Maria Cantwell of Washington, the top Democrat of the Senate Energy and Natural Resources Committee, in a press conference Thursday. “In this process, we know the deck is stacked as it is. The only way they have been able to get any place on this issue is to throw away the regular process. The notion we can be this close to losing something so unique, such an unbelievable treasure, because it gets buried... in a crazy tax bill is one of our biggest challenges.”

Sen. Lisa Murkowski, R-Alaska, introduced legislation Wednesday night to open the 1002 area of the wildlife refuge to oil and gas drilling, with the expectation that energy development there will raise about $1 billion over 10 years.

The introduction of the bill fulfills the terms of a budget resolution passed by the GOP-controlled House and Senate that directed the Energy and Natural Resources Committee, which Murkowski leads, to create legislation to raise $1 billion over a decade to help pay for tax reform.

Murkowski said her committee will mark up the legislation Wednesday.

“This legislation is a tremendous opportunity for both Alaska and our country,” Murkowski said.

The refuge was created under former President Dwight D. Eisenhower in 1960. In 1980, Congress provided additional protections to the refuge but set aside the 1002 area for future drilling if lawmakers approved it.

Murkowski's bill requires the Interior Department to hold at least two lease sales within 10 years of the bill's passage, the first within four years and the second within seven years.

It says that lease sale areas should include at least 400,000 acres with a strong potential for drilling. But surface development would be limited to 2,000 acres of the coastal plain.

The bill would split in half revenue raised from energy development between Alaska's government and the federal government.

Alaskan politicians are especially eager to tap the refuge because oil production in the state has fallen from more than two million barrels per day in the late 1980s to under a half-million barrels per day — a big deal in a state whose government provides residents an annual check from oil revenue.

Cantwell suggested the provision giving half of revenue to Alaska could prompt some Republicans to oppose the bill. Democrats authored an amendment last month to the budget resolution blocking drilling in the refuge, but the measure failed with only one Republican, Sen. Susan Collins of Maine, voting with them.

“We don't know where everybody is going to be on a final vote,” Cantwell said. “Several members are now saying [they] didn't realize this was the structure, that we're giving Alaskans basically the opportunity to get well on the revenue that may come out of this. Now when the details come out, members may look at it differently.”

Many former government officials, Democrats and environmental groups doubt drilling in the refuge can meet Republicans’ revenue expectations. That’s because oil prices are hovering just above $50 a barrel and competition is fierce from natural gas in the nation's shale regions.

“In order to raise the revenue Republicans’ project, it would need to bring in 10 to 100 times the historical average of what oil companies have paid to drill in Alaska,” said Sen. Ed Markey, D-Mass., at the Thursday press conference. “The only thing fuzzier than the polar bears that call the refuge home is the Republican drilling mathematics.”

The Congressional Budget Office estimates the legislation would raise $1.092 billion over the 10-year budget window. Between royalties and federal income taxes, energy development would “raise substantially greater revenues,” Murkowski insists.

Cantwell and fellow Democrats realize they are limited in what they can do and are already looking ahead to the next fight.

“The question we will raise is what's next?” Cantwell said. “What other refuge in America will you mandate drilling in?”