The Obama administration is approaching a weekend deadline to decide whether it should allow government agencies to cite the federal Endangered Species Act, which protects the bear, for imposing limits on greenhouse gases from power plants, factories and automobiles even if the pollution occurs thousands of miles from where the polar bear lives.

The species law that affords protection for plants, animals and fish that face possible extinction became entangled with the need to reduce pollution linked to global warming more than a year ago. The Interior Department declared the polar bear a threatened species, citing the decline of Arctic sea ice due to global warming.

Fearful that the declaration putting the bear under the federal species law might be used to force regulation of carbon dioxide, the leading greenhouse gas from burning fossil fuels, the Bush administration issued a special rule: No action outside of the bear's Arctic habitat could be considered as endangering its survival.

The limitation, hailed by business groups, prompted lawsuits from environmentalists and action by Congress.

In March, federal lawmakers authorized Interior Secretary Ken Salazar to rescind the Bush administration's special rule, thus avoiding any complicated and time-consuming regulatory procedures. The deadline for such action is Saturday, 60 days after Congress acted.

Salazar was said to be weighing the issue. Lobbying on the matter has been heavy, and Salazar has given little hint on whether he will rescind the Bush rule.

Environmentalists complained last week when Salazar failed to address the polar bear rule when he rescinded another Bush regulation involving endangered species consultation, one Congress also authorized to be scrapped.

"From our perspective the job is half done" without a reversal of the polar bear rule, Noah Greenwald of the Center for Biological Diversity, an advocacy group, said after last week's action.

The special rule "significantly undercuts protections for the polar bear by omitting global warming pollution as a factor in the polar bear's risk of extinction,'' said Jane Kochersperger, a spokeswoman for Greenpeace, which delivered 80,000 petitions to the Interior Department after they were collected by the two environmental groups.

Environmentalists also circulated a letter to Salazar, signed by 49 law professors, that urges him to reverse the Bush rule, arguing that its restrictions are so broad as to be illegal under the Endangered Species Act.

Business groups have expressed concern about the Endangered Species Act being used to regulate greenhouse gases, especially industrial and power plant emissions.

On Thursday, Rep. Doc Hastings, the ranking Republican on the House Natural Resources Committee, urged Salazar to keep the Bush rule in place.

Along with the recent ruling by the Environmental Protection Agency that carbon dioxide is a health hazard, "withdrawing this rule would give the federal government vast new climate change power to regulate any federal or federally permitted activity in our country that emits greenhouse gases,'' said Hastings. "This reaches far beyond the scope of polar bears in the Arctic and could put jobs and economic activity across the entire nation at risk."