ANCHORAGE, Alaska (AP) — Melting summer sea ice is opening up the Arctic Ocean to commercial opportunities but the United States could miss them if it doesn't sign the Law of the Sea treaty, according to U.S. Sen. Lisa Murkowski.

The Alaska Republican hopes the Senate will vote to sign the treaty during the lame duck session following the November election.

The treaty sets up a system for resolving disputes in international waters. It has been around since the Reagan administration, and 162 countries have signed on.

"This is a treaty that I believe very strongly will contribute not only to our national security, but will allow us a level of certainly in accessing our resources in the north," Murkowski said Wednesday. The Constitution requires two-thirds of the Senate — 67 votes — to ratify a treaty.

The treaty recognizes sovereign rights over a country's "exclusive economic zone" — the area covering its continental shelf out to 200 nautical miles. It recognizes rights beyond that zone if the country can provide evidence to substantiate its claims.

That's exactly what could happen off Alaska's northern shore, Murkowski said. Outer continental shelf mapping indicates the United States could claim an area the size of California, she said.

"I don't want us as an Arctic nation to abandon those opportunities, and we would be doing that if we fail to ratify the Law of the Sea treaty," Murkowski said.

The treaty has support from the president, most Senate Democrats, the U.S. Chamber of Commerce, and the military.

"Anybody with a star on their shoulder has sat before the Foreign Relations Committee and testified about why it's so important, so critical, to this nation," she said.

She has worked with Sen. John Kerry, D-Mass., to educate fellow senators on the pact's importance. Proponents faced a setback in June, she said, when Sens. Rob Portman, R-Ohio, and Kelly Ayotte, R-N.H., said they had concerns about the breadth and ambiguity of the treaty and that it was not in the national interest at that time. Their decision meant opponents had enough votes to block ratification unless some senators change their minds.

In the upcoming months, Murkowski said, representatives from shipping, telecommunications, petroleum and even tourism interests will make the case for the treaty.

She said opponents are not worried U.S. interests could be exposed to international litigation. Instead, she said, they see a loss of U.S sovereignty if the United Nations is involved.

"There are some colleagues — if the United Nations is in the title of any treaty, it's an automatic no," Murkowski said. "But the reality is the treaty has been amended or adapted from the time President Reagan was in office, and had concerns about it, to address some of the issues that have been raised."

The chance of treaty approval in November or December, she said, will depend on whether special interests, such as the U.S. Chamber, push the measure as a priority over other legislation such as automatic deficit reduction or tax cut extension.

"The concern is, we have these advocates, but they're going have to prioritize what they're going to be pushing for hardest," Murkowski said.