WASHINGTON (Reuters) - Democrat John Kerry (news - web sites)'s presidential campaign accused the Bush White House on Wednesday of disclosing the existence of a criminal investigation against former national security adviser Sandy Berger for political advantage. The objective of such a leak, the Kerry campaign said in a political memo distributed by email, was to take attention away from a report to be issued on Thursday by the commission investigating the Sept. 11, 2001, attacks. The criminal investigation of Berger began last October but only came to light this week. "The timing of this leak suggests that the White...