The leader of opposition Democrats in the U.S. Senate says the Bush administration needs to explain what role it had in the exposure of a covert CIA officer.

Interviewed Sunday on the ABC television program "This Week," Senator Harry Reid said President Bush and Vice President Dick Cheney "come clean with the American public."

Mr. Reid also said the president should pledge not to pardon Mr. Cheney's former chief of staff Lewis Libby if he is convicted.

Mr. Libby resigned Friday after being indicted on five charges in connection with statements he made to investigators probing the CIA leak.

Both the president and Mr. Cheney have refused to comment on the probe.

Senator Reid also called for the resignation of Mr. Bush's chief adviser, Karl Rove. Mr. Rove has not been charged with a crime in the probe but reportedly remains under investigation.