The first U.S. legislation in four years to propose oil and gas exploration inside the Arctic National Wildlife Refuge is on thin ice, says a pro-protection lobbyist for ANWR.

Cindy Shogan of the Alaska Wilderness League said today the Republican-sponsored transportation bill before the House of Representatives is a long-shot from passing this week as it is.

Even if it does, there's still an uphill climb before the legislation would ever see the light of day on the floor of the Senate, the executive director said from her office in Washington, D.C.

Shogan said the Senate is advancing its own transportation bill which does not include a provision to drill inside the refuge, situated in northern Alaska along the Yukon-Alaska border.

It's the first time since 2008 that any legislation, either through the House of Representatives or the Senate, has included a provision to open up ANWR to oil and gas exploration for the purpose of raising revenue, she pointed out.

Shogan said there seems to be a growing distaste in the U.S. capitol for using ANWR as a source of revenue to support other domestic initiatives.

Even Alaska Republican Senator Lisa Murkowski, a supporter of development inside the refuge, spoke a couple of weeks ago against including such a provision during preparation of the Senate's own transportation bill, she pointed out.

Shogan also noted the recent letter to Republican leaders signed by several Republicans in the House of Representatives indicating they believed their transportation bill would be better off without the ANWR provision.

Under the U.S. legislative process, bills require the support from both the Senate and House of Representatives.

If, for instance, both legislative bodies pass their respective transportation bills, then it becomes a matter of negotiating one bill that both the House and the Senate can live with.

Shogan said if the House of Representatives controlled by the Republicans passes its bill with ANWR, it would still have to go through the Senate controlled by the Democrats, the majority of whom traditionally favour protection of the refuge.

"It's impossible to tell where the votes are,” Shogan said of trying to figure who in the House favours the bill and who doesn't.

"I do not see it going any further than that, even if it passes the floor.”

An article appearing today in Washington's The Hill indicates the Republicans are struggling to find the 218 votes among their rank-and-file in the House of Representatives to pass the bill in its current form.

Shogan said the Republicans have said they want the vote this week before the House recesses but she doubts they'll bring it to the floor without enough support.

The Republican proposal calls for the expenditure of $260 billion US on highways, bridges and other infrastructure, though there's also concern that some on the conservative right might view the amount as too much government largesse.

As a means of raising additional review, the bill proposes to open up ANWR and provide for more drilling opportunities in the Gulf of Mexico.

The Senate's transportation bill proposes expenditures of $109 billion.

Shogan said the last time ANWR was included in a piece of legislation as a source of revenue was in 2008.

The Vuntut Gwitchin First Nation of Old Crow has been front and centre – along with Gwitchin across the North – in the lobby for the protection of the wildlife refuge.

The Yukon government has also expressed its opposition to opening up ANWR.

The refuge provides crucial calving habitat for the Porcupine caribou herd.

Many feel permitting development would inevitably threaten the herd and a valuable source of food for the Gwitchin, whose culture is also tied the caribou.

It hasn't been uncommon over the years for the ANWR provision to show up in legislation that has nothing to do with Alaska, oil and gas, wildlife or the environment, and was once buried in a U.S. defence bill several years ago.