Para. 2-9(a) of Army Regulation 70-13 (July 2010) states: "All service contract actions must be documented on a Request for Civilian Hire or Services Contract Approval Form and approved in advance of contract award." The Summary section of the same regulation states: "This regulation prescribes Armywide policies and responsibilities for management and oversight of all services contract acquisitions."  In other words, I could not find any exceptions based on the scenario you provided. Please check with your local Contract Policy office for a more authoritative response.