California Democrat Barbara Boxer blasted Interior Secretary Dirk Kempthorne for failing to show up Wednesday at a hearing on polar bears and global warming.

The Interior Department has delayed making a decision on whether the polar bear should be listed under the Endangered Species Act, prompting Boxer, who chairs the Environment and Public Works Committee, to invite Kempthorne to discuss the issue. Environmentalists have sued the Bush administration for failing to meet a legal deadline of Jan. 9 to make a decision.

In an April 1 letter to Boxer, Kempthorne said he would not attend the hearing because it would compromise his position in the lawsuit. He did agree to testify once the Bush administration makes a final decision on listing the polar bear.

“Time has run out for this decision to be made,” Boxer said. “Mr. Kempthorne not being here, I believe, is a slap at this committee and a slap at the American people who care about this.”

Kempthorne wrote that it would not be appropriate for him to testify until the administration makes a decision, though he did not provide a date.

“I am, in my official capacity, one of the named defendants in litigation on the matter that is the subject of the hearing,” he wrote. “In fact, one of the other witnesses at the hearing is a representative of one of the plaintiffs in that case.”

Environmental groups maintain the polar bear is threatened because of decreasing sea ice in the Arctic under global warming. The U.S. Fish and Wildlife Service issued a proposal to list the species in January 2007 and received more than 670,000 comments from the public.

The panel’s ranking Republican, James M. Inhofe of Oklahoma, defended Kempthorne’s decision not to appear. “He has not shirked his duty to appear; in fact, he has agreed to appear before this committee when the decision is made,” Inhofe said.