Proponents of the measure fell four votes shy of securing the 60 votes needed to end debate and proceed to a vote on the bill, which contains a controversial provision introduced by Alaska lawmakers that would permit oil drilling in the Arctic National Wildlife Refuge (ANWR).

A new vote could be held Wednesday if the measure's backers agree to withdraw it, paving the way for the rest of the bill to be considered.

President George W. Bush's administration has insisted that opening the area to exploration would help reduce US dependence on imported oil at a time when crude prices have spiked dramatically.

Environmentalists, however, have argued that drilling in ANWR would yield relatively little oil and would permanently despoil the pristine nature refuge.