The U.S. House Natural Resources Committee approved Resolution Copper’s proposed land swap with the federal government on May 15, eight years after it was first introduced.

The bill, backed by former political rivals Reps. Paul Gosar (R-AZ) and Ann Kirkpatrick (D-AZ), passed the House Natural Resources Committee by a vote of 23 to 19. It is expected to move to the House floor for a vote later this year. If approved, it would allow Resolution Copper to exchange more than 2,000 ha (5,000 acres) of environmentally sensitive land it owns throughout Arizona for about 971 ha (2,400 acres) of federal land near Superior. The company would develop a 2,000-m- (7,000-ft-) deep mine there, opening the third-largest undeveloped copper resource in the world.

“This land exchange and conservation bill is the direct result of years of negotiations, an open process and a common vision amongst its supporters to bring good paying jobs to Arizona,” Gosar said after the vote.

The committee approved the copper mine project in July 2011 and sent it to the full House, where it passed three months later and is likely to pass again in this session. The bill died in the Senate, where its future remains uncertain, Azcentral.com reported.

The vote on May 15 by the House panel was the first step in reviving the Southeast Arizona Land Exchange and Conservation Act.

Meanwhile, continued uncertainty over the mine’s future prompted Resolution Copper Mining Co. to lay off more than 200 of its 540 workers since November. The number of employees will drop to 140 by year’s end if the project is not approved, developers have said.

“I’m optimistic this bill will pass the full House, but there’s more work to be done with our colleagues in the Senate,” Kirkpatrick said. “I will continue to provide a voice for the mining communities, tribes and environmental groups in my district who have many perspectives on the Superior Mine project. I believe we can create these good jobs while also respecting and addressing outstanding concerns.”

Supporters — including the Pinal County Board of Supervisors — say the project would create 3,700 jobs and contribute $61.4 billion in economic activity to Arizona over the mine’s projected 66-year life span. An estimated $19 billion in tax revenue would be generated for state, local, and federal governments over the life of the mine.

But the San Carlos Apache Tribe and other Native American and environmental groups worry the mine would threaten the region’s water supply, harm sacred tribal grounds and destroy land in the Tonto National Forest enjoyed by campers and rock climbers. They also question how many local jobs it will actually create.

“Indian Country has spoken up and said they don’t want this,” said Rep. Markwayne Mullin, R-Okla., who is a member of the Cherokee Nation and the only Republican on the committee to vote against the bill. “We should listen to them.”

Grijalva proposed several amendments to the bill, including one that would have required the mine operations center — which controls robotics at the mine — to be located in Superior. A second would have required a full environmental review of the proposed mine before the land swap instead of afterward. All of his amendments failed.

Resolution Copper has said it intends to station its mine operations — including remote operators who control robotics — at the local mine site. Gosar said the proposed mine would have to go through a thorough environmental review by federal agencies before it can move forward under his bill.