FWS Director Dale Hall said the agency hopes to have a recommendation within weeks so that Interior Secretary Dirk Kempthorne can announce his decision within a month, reported the Associated Press.
The agency has never labeled a species threatened or endangered due to global warming, which has complicated the matter, said Hall.
Environmental groups that filed the petition to get the bear listed said they intend to file a formal notice to sue as required under the Endangered Species Act.
"We certainly hope that the polar bear will be listed within the next month," said Kassie Siegel, an attorney for the Center for Biological Diversity -- the lead author of the petition, quoted the AP. "But this is an administration of broken promises, from Bush's campaign pledge to regulate greenhouse gases to Secretary Kempthorne's failure to list a single species under the Endangered Species Act in the last 607 days."
Hall said he did not like missing the deadline, but "it is far more important" to make the decision correctly and explain it properly to the public in the Federal Register.
The agency sought additional information about the polar bears' habitat from the U.S. Geological Survey and received nine studies in September. One study concluded that two-thirds of the world's polar bears, including the entire population in Alaska, would be killed off by 2050 because of thinning of sea ice from global warming in the Arctic.
FWS then extended the public comment period so that people could respond to the studies.