WASHINGTON — As another fevered push to open the pristine Arctic National Wildlife Refuge to energy exploration collapsed on the Senate floor in December 2005, Ted Stevens, then the powerful and wily Republican senator from Alaska, declared it “the saddest day of my life.”

At that moment, it looked as though the decades-long fight over drilling in 1.5 million acres of the remote refuge could finally be at an end. Republicans essentially gave up for the remainder of the George W. Bush administration after Democrats won control of Congress, and the drilling proposal had no chance during the Obama years, so it virtually disappeared as a topic of congressional conversation.

Now, almost out of nowhere, determined backers of drilling are on the verge of a remarkable comeback victory, nearing approval of the long-sought measure as part of the tax plan being negotiated between the House and Senate. The fight has a symbolic significance that is almost impossible to overstate, pitting the nation’s leading environmental groups against Alaskan lawmakers and energy companies over a slice of tundra on the North Slope of Alaska that is home to abundant wildlife, including caribou and polar bears.

This latest effort has two distinct advantages for drilling proponents. It avoids a certain Democratic filibuster because of special rules being applied on the floor for considering the tax bill. And it simultaneously secures the vote of Senator Lisa Murkowski for the tax measure.