Appointment and Confirmation of Executive Branch Leadership: An Overview [June 22, 2015] [open pdf - 286KB]
"The Constitution divides the responsibility for populating the top positions in the executive branch of the federal government between the President and the Senate. Article II, Section 2 empowers the President to nominate and, by and with the advice and consent of the Senate, to appoint the principal officers of the United States, as well as some subordinate officers. […] The President may also be able to fill vacancies in advice and consent positions in the executive branch temporarily through other means. If circumstances permit and conditions are met, the President could choose to give a recess appointment to an individual. Such an appointment would last until the end of the next session of the Senate. Alternatively, in some cases, the President may be able to designate an official to serve in a vacant position on a temporary basis under the Federal Vacancies Reform Act or under statutory authority specific to the position. Congress has selectively included certain types of statutory provisions when establishing specific executive branch positions. These provisions include those that require appointees to have specified qualifications, that set fixed terms of office, that limit the circumstances under which the President can remove an officeholder, that specify how the chair of a collegial board or commission will be selected and may be removed, and that allow an incumbent to remain in office past the end of a term until a successor is appointed (hold over)."
CRS Report for Congress, R44083
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html