The guests debated Congress' constitutional powers to limit or end the war in Iraq as proposed in several resolutions that may be debated next week in the Senate. Mr. Dellinger testified at a Senate Judiciary Committee on this topic and said that Congress may set limits on the president’s discretion about the scope and duration of military action. Mr. Rivkin, who wrote an opinion piece in the January 31 Wall Street Journal, said Congress does not have the authority to limit or end the war. They responded to telephone calls and electronic mail.