A provision to allow oil and gas exploration in a portion of Alaska's Arctic National Wildlife Refuge passed the U.S. Senate as part of the Republican tax bill early Saturday morning.

The controversial provision, which was added by Sen. Lisa Murkowski, an Alaska Republican, survived a push in October led by Sen. Maria Cantwell, a Washington state Democrat, to remove it.  It also required some last-minute revisions to satisfy arcane Senate procedural rules.

Alaska's congressional delegation praised the provision's inclusion in the final version of the Senate bill.

"Opening the 1002 Area and tax reform both stand on their own, but combining them into the same bill, and then successfully passing that bill, makes this a great day to be an Alaskan," Murkowski said in the statement.

Conservation groups, meanwhile, blasted the move.

In a statement, Audubon Society President and CEO David Yarnold called the move " simply shameful." and added that "The Arctic Refuge isn't a bank—drilling there won't pay for the tax cuts the Senate just passed."

The provision must now survive reconciliation with the House's version of the tax overhaul in a conference committee.

While the House is more solidly Republican—and ANWR votes have usually broken mostly along party lines—several Republican members of the House sent a letter on Thursday to Congressional leaders urging them not to open the refuge to drilling.