Advocates who have followed the case say the issue went back and forth within the Interior Department, with some staff members arguing that the bears were clearly threatened by melting sea ice and others saying it would be politically dangerous to invoke the Endangered Species Act.
They argued that protecting bears in this way might, in effect, push the U.S. Fish and Wildlife Service into the position of regulating the emissions of carbon dioxide from cars and industry — something that clearly does not fall under its jurisdiction.
Kempthorne said today that he would make sure that does not happen.
"The president is absolutely right," he said. "Listing the polar bear as threatened can reduce avoidable losses of polar bears, but it should not open the door to use the E.S.A. to reduce greenhouse gas emissions."