Dec 18 The agency that acts as the U.S. government's landlord and realtor has asked regulators in the District of Columbia to reject the merger of utilities Exelon Corp and Pepco Holdings Inc, unless it provides a better deal for taxpayers, the Washington Post reported. Attorneys for the General Services Administration said the deal subsidizes the rates of residential customers at the expense of federal taxpayers, the Post said, citing filings it had reviewed.