what is "Doctrine of Political Agency"

Under this doctrine, which recognizes the establishment of a single executive, all executive and administrative organizations are adjuncts of the Executive Department, the heads of the various executive departments are assistants and agents of the Chief Executive, and, except in cases where the Chief Executive is required by the Constitution or law to act in person or the exigencies of the situation demand that he act personally, the multifarious executive and administrative functions of the Chief Executive are performed by and through the executive departments, and the acts of the Secretaries of such departments, performed and promulgated in the regular course of business, are, unless disapproved or reprobated by the Chief Executive, presumptively the acts of the Chief Executive