Senate Republicans passed legislation early Saturday allowing oil and gas drilling in the Arctic National Wildlife Refuge as part of a tax reform package, moving closer to fulfilling a long-time GOP goal.

The passage of the bill marked a significant achievement for Sen. Lisa Murkowski, R-Alaska, the chairwoman of the Senate Energy and Natural Resources Committee, who has introduced legislation to open a portion of the Alaskan refuge to drilling every term she has served in the chamber, only to be blocked by Democrats.

“This small package offers a tremendous opportunity for Alaska, for the Gulf Coast, and for all of our nation,” Murkowski said before the vote. “We have authorized responsible energy development in the 1002 area.”

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 acres of ANWR known as the “1002 area,” where billions of barrels of crude oil lie beneath the coastal plain.

But this year, Republican control of Congress and the White House spurred Senate Republicans to consider the provision with the tax reform measure under budget reconciliation rules that allow it to avoid a filibuster and pass with a simple majority vote.

Senate Democrats have blasted the process Republicans used to advance the ANWR bill, considering it an unfair way to change the character of a refuge that has been protected since 1960.

Democrats and environmentalists say drilling would harm the ecosystem of what they describe as one of the wildest places left on earth, inhabited by animals such as polar bears, caribou, and arctic foxes.

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

“We don't think this has been a fair and open process,” said Sen. Maria Cantwell of Washington, the top Democrat on the Energy and Natural Resources Committee, in a press conference leading up to the vote. “The only way they have been able to get any place on this issue is to throw away the regular process.”

Cantwell was the key lawmaker who blocked Republicans the last time they came close to drilling in ANWR, when in 2005 she imposed a filibuster stopping a provision in a military spending authorization bill that would have opened the refuge.

Senate Republicans almost failed again this week when they ran into procedural hurdles in trying to include the ANWR provision with tax reform.

Murkowski had to resubmit a second version of the ANWR bill because the Senate parliamentarian determined the original version as it was advanced by the Environment and Natural Resources Committee last month violated the Byrd Rule governing budget reconciliation.

Because of that violation, Republicans determined the ANWR provision would fall short by about $366 million of raising $1 billion during the 10-year budget window.

The Republican-controlled Congress in its budget resolution directed the Energy and Natural Resources Committee to create the ANWR legislation so that it raises $1 billion over a decade to help pay for tax reform.

To make up for that lost revenue, Republicans decided to sell seven million barrels of oil from the Strategic Petroleum Reserve.

The new version of the bill, like the original, would permit drilling in 2,000 acres of the 1002 area of the refuge and split the expected revenues over the next decade between Alaska and the federal government.

Murkowski's bill requires the Interior Department to hold at least two lease sales within 10 years of the bill's passage.

Democrats and environmental groups argue that drilling in the refuge cannot meet Republicans' expectations of raising $1 billion for the government over 10 years, with low oil prices and steep competition from natural gas.

Opponents also question energy companies’ safety record drilling in Alaska.

But 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.

Murkowski stresses that modern innovations such as horizontal drilling will allow energy companies to safely extract oil in the refuge.

“There are some who worry about the potential impacts of development,” Murkowski said in a floor speech Thursday night. “I would be the first to agree local wildlife will always be a concern. That is why we did not waive NEPA or other environmental laws. We will not sacrifice wildlife or the environment for the sake of development.”

The Senate still needs to reconcile its ANWR bill with the House.

The prospects in the House were challenged Thursday after a dozen moderate House Republicans wrote to GOP leaders expressing opposition to the ANWR drilling plan.

Members signing the letter include Reps. Dave Reichert of Washington; Brian Fitzpatrick, Ryan Costello, and Pat Meehan of Pennsylvania; Carlos Curbelo of Florida; and Mark Sanford of South Carolina.

Each lawmaker supported the House tax package reform package when it passed last month, but expressed unease with the ANWR provision as it moved through the Senate.

House Republicans can afford only 10 additional defections from the November tax reform bill vote tally for the final package to pass.