The Arctic National Wildlife Refuge, which covers more than 19 million acres of pristine land in northeastern Alaska, has long been a symbol of the tug between conservation and commerce.

The refuge is an ecological marvel, home to caribou, polar bears, grizzly bears, snow geese and peregrine falcons. But about 1.5 million acres of coastal plain, which has yet to receive wilderness protection, has the tantalizing potential to produce a vast trove of oil and natural gas.

Alaska has sought to explore the refuge’s coastal plain for oil and natural gas development, but has been blocked by the U.S. Department of the Interior, Congress and conservationists who want to preserve the region. The dispute has also divided Alaska Natives.

The Inupiat, who live in Kaktovik, a village in the refuge, own land ripe for oil and natural gas exploration. The Gwich’in, who live in Arctic Village, just outside the refuge, fear that development could disrupt the caribou they depend on for survival.

For years, Hawaii’s two U.S. senators — Daniel Inouye and Daniel Akaka — sided with Alaska and the Inupiat, part of a political alliance between the two states in Washington, D.C., that spanned a generation. But with Inouye dead and Akaka retired, the dynamics have changed.

U.S. Sen. Brian Schatz and U.S. Sen. Mazie Hirono, who replaced Inouye and Akaka last January, strongly oppose oil and natural gas drilling in the Arctic Refuge. U.S. Rep. Colleen Hanabusa, who is challenging Schatz in the Democratic primary for U.S. Senate, favors limited drilling so the Inupiat might have the opportunity to economically benefit from their land.

The policy difference between Schatz and Hanabusa might appear to be an arcane one in the context of their primary, but it hints at how the Democrats weigh the environment, clean energy, native rights, states’ rights and a partnership between Alaska and Hawaii in Congress that has proved mutually rewarding.

"Simply put, it’s time for us to move forward with a clean energy economy, not to be more aggressive with drilling for oil," Schatz said in a telephone interview from Washington.

"We have the technology and we’re in the process of transforming the American economy to utilize less fossil fuel. In America’s history, we’ve never gone back after designating an area a refuge to allow oil drilling.

"And this would do nothing for price. It will not lower today’s gasoline prices and won’t solve our long-term energy needs."

Hanabusa voted against a move by the U.S. House in February 2012 to potentially open up all of the Arctic Refuge’s coastal plain to oil and natural gas development. But she contends the Inupiat should have the right to decide on limited development of their portion of the land — a right conditioned on congressional approval.

The Kaktovik Inupiat Corp., through a series of agreements involving the federal government, relinquished land outside the refuge, selected land inside the refuge, and exchanged rights with the Arctic Slope Regional Corp. in the expectation of future development.

"We cannot give them the right to pick and to live there, and then turn around and then basically annihilate their rights to survive," the congresswoman said by phone from Washington, comparing it to protecting Native Hawaiian rights. "We can’t do that. It’s just not right."

In late October, Interior Secretary Sally Jewell said in a speech at the National Press Club that the Arctic Refuge is one of the places that is "too special to develop."

This month, U.S. Sens. Maria Cantwell, D-Wash., and Mark Kirk, R-Ill., introduced a bill that would apply a wilderness designation to the 1.5 million acres of the refuge’s coastal plain, which would preserve critical habitat while closing off oil and natural gas development.

U.S. Sen. Mark Begich, D-Alaska, said in a letter to Jewell that he would fight any effort by the Obama administration to make the refuge off-limits to development.

U.S. Sen. Lisa Murkowski, R-Alaska, told the Juneau Empire newspaper that the Cantwell and Kirk bill was "anti-Alaska legislation" that ignores the nation’s need for jobs, revenue and domestic sources of energy.

Oil production in Alaska has declined over the past two decades, from a peak of more than 2 million barrels a day in 1988 to 526,000 barrels a day last year. Alaska offered tax incentives this year for oil companies to invest in exploration, hoping to keep the flow of oil lease and royalty money that allows the state to have no personal income tax or state sales tax.

The Arctic Refuge was created in 1960 and widely expanded as a conservation jewel in 1980, when Congress also ordered wildlife studies and oil and natural gas assessments of the 1.5 million acres of coastal plain. The Kaktovik Inupiat Corp. owns about 92,000 acres in the coastal plain.

Estimates have suggested that the coastal plain could yield up to 11 billion barrels of oil but the region has not been recently tested. (The U.S. consumes about 7 billion barrels of oil a year.) Last summer, the Interior Department’s U.S. Fish and Wildlife Service denied a request from Alaska Gov. Sean Parnell that the state conduct new seismic tests for oil and natural gas.

Renewed interest in natural gas as an energy resource in the continental United States — and the fight between the industry and environmentalists over hydraulic fracturing, or "fracking" — has taken some of the urgency away from the national debate over the Arctic Refuge. But the refuge has powerful symbolic importance to conservationists and continues to be politically sensitive in Alaska, where many resent the national intrusion.

While Hanabusa — like Akaka — has framed the issue of drilling in the Arctic Refuge as self-determination for the indigenous Inupiat, the history is complicated.

Others — like Schatz, Cantwell, Kirk and many conservationists — argue that preserving the coastal plain will help the Gwich’in, a native tribe that subsists off the Porcupine caribou herd that roams through the refuge. The caribou are known to give birth and nurse in the coastal plain.

But the Gwich’in also flirted with oil and natural gas exploration in the 1980s before emerging as the leading opponents of drilling in the refuge. The Gwich’in in Canada remain open to exploration in the Northwest Territories.

The partnership between Hawaii and Alaska in Congress was forged in the 1960s by Inouye and the late U.S. Sen. Ted Stevens, R-Alaska, who understood that the two newest states should work together to maximize influence in Washington. Inouye and Akaka were among the few Demo­crats to back drilling in the Arctic Refuge, for example, while Stevens and U.S. Sen. Frank Murkowski, R-Alaska — and now his daughter, Lisa Murkowski — were among the few Republicans to support Native Hawaiian federal recognition.

The alliance was not just about vote trading; it was about deciphering the nuances of Hawaii and Alaska for other senators who often see the unique states as postcard caricatures.

Both Schatz and Hanabusa say they want to maintain Hawaii’s partnership with Alaska.

Schatz, who considers Begich among his closest friends in the Senate and serves with Murkowski on the Senate Energy and Natural Resources Committee, said the relationship is important for both states.

"We have strong personal bonds and strong political ties, and they are not defined by any one issue," Schatz said.

Hanabusa said Hawaii and Alaska share a deeper understanding of the struggles of indigenous people.

"We know that we have to fight for those rights, even if it means getting blasted by environmentalists because we’re not doing what they think is a no-brainer," she said. "It is not simple. It is a people. And it is the culture. And they are so tied to their land."