Burson-Marsteller, run by Clinton pollster Mark Penn, has been representing the troubled security firm in the lead-up to congressional testimony this week in which top company officials defended their policies and techniques for providing security in the war zone.

Penn is one of Clinton's longest-serving and most important advisers, perhaps second only to her husband in influence. He said yesterday that his company was no longer representing Blackwater. Listed as the "worldwide CEO" of the company, Penn also said he was not personally involved in the account.