48 CFR § 1.601 - General.
(a) Unless specifically prohibited by another provision of law, authority and responsibility to contract for authorized supplies and services are vested in the agency head. The agency head may establish contracting activities and delegate broad authority to manage the agency's contracting functions to heads of such contracting activities. Contracts may be entered into and signed on behalf of the Government only by contracting officers. In some agencies, a relatively small number of high level officials are designated contracting officers solely by virtue of their positions. Contracting officers below the level of a head of a contracting activity shall be selected and appointed under 1.603.
(b) Agency heads may mutually agree to -
(1) Assign contracting functions and responsibilities from one agency to another; and
(2) Create joint or combined offices to exercise acquisition functions and responsibilities.