The chair of the Senate Environment Committee Wednesday slammed Interior Secretary Dirk Kempthorne for failing to appear before her panel to explain why the Bush administration has delayed a decision on whether to protect polar bears under the Endangered Species Act.

Sen. Barbara Boxer, D-Calif., said it was "wrong" that Kempthorne declined her invitation to appear before the Senate Committee on Environment and Public Works.

"It's wrong that Mr. Kempthorne is not here," Boxer said after the hearing, which went on without an appearance from Kempthorne or any other administration official. "I like him, but it's wrong."

The deadline for a decision on listing Alaska's polar bears as threatened under the Endangered Species Act was Jan. 9. Conservation groups petitioned to list polar bears as threatened more than three years ago because their habitat, sea ice, is shrinking from global warming.

Boxer said Kempthorne and other administration officials were "ducking their responsibility to the American people" by delaying a decision on the bears - and then failing to appear at a hearing to explain why.

Boxer said she was especially troubled because the administration did not hesitate to open a major bear habitat to oil leases. The Interior Department opened a large area of the Chukchi Sea to oil and gas leases in early February, despite sharp criticism from environmentalists who note that one-fifth of the Arctic's polar bears depend on sea ice in their hunt for food.

"There's a rush to drill, and no rush to list" polar bears as threatened, Boxer said.

A spokesman for Kempthorne declined immediate comment, but in a letter to Boxer, Kempthorne said he "respectfully" declined her invitation to appear at the hearing, since he is a named defendant in a lawsuit over the polar bear listing filed by an environmental group.

Kempthorne, a former Idaho governor and senator, said he understands that the delay in the polar bear decision is frustrating to Boxer and others who advocate additional protections for the bear.

But he said the oil and gas leases opened up in February do not pose a threat to the bear, citing the "localized nature" of the proposed oil and gas developments. If the bear is listed as threatened, any oil and gas exploration would be subject to the Endangered Species Act, regardless of when the leases are sold, Kempthorne said.

Sen. John Warner, R-Va., said he spoke with Kempthorne this week, and Kempthorne expects a decision on polar bears "before early summer."

The Interior Department's inspector general, responding to conservation groups, said last month it is investigating why the department had not made its listing decision.