The U.S. Interior Department is auctioning off oil and gas leases on Wednesday to drill in Alaska’s Chukchi Sea, despite opposition from environmentalists and some Democrats in Congress concerned about the impact on polar bears. The Chukchi Sea, off Alaska’s northern coast, is prime polar-bear habitat and advocates worry that already-stressed bear populations will fare even worse in the event of a spill or other exploration-related disruption. A decision on whether to list the polar bear as threatened under the Endangered Species Act was expected weeks ago, but has been stalled. The agency responsible for the ESA listing decision and the agency in charge of offshore oil leases are both part of the Interior Department. Critics of the Chukchi leases have accused the Bush administration of deliberately halting the ESA listing decision until after the oil-lease auction. The Interior Department suggests it just wants to be thorough. Efforts to stop the lease sale have been ineffective so far, though bear advocates sued to force the agency to reassess the effects of oil and gas leasing in the Chukchi Sea.