A ccording to the 2016 edition of the Plum Book , more than 1,000 executive branch positions are filled through appointment by the President with the advice and consent of the Senate (herein, advice and consent positions). The Constitution and federal statutes provide several authorities for temporarily filling vacancies in these positions: the Federal Vacancies Reform Act of 1998 (Vacancies Act); the President's constitutional recess appointment power; and position-specific temporary appointment provisions. Each of these authorities is discussed below. When an executive branch advice and consent position covered by the Vacancies Act becomes vacant, it may be filled temporarily in one of three ways under the act: (1) the first assistant to such a position may automatically assume the functions and duties of the office; (2) the President may direct an officer who is occupying a different advice and consent position to perform these tasks; or (3) the President may select an officer or employee who is occupying a position, in the same agency, for which the rate of pay is equal to or greater than the minimum rate of pay at the GS-15 level, and who has served in that agency for at least 90 days during the year preceding the vacancy. In general, a temporary appointment under the Vacancies Act continues until no later than 210 days after the date the vacancy occurred or, if the vacancy occurred during a Senate recess, 210 days after the date the Senate reconvenes. The time restriction is suspended, and the acting officer can continue to serve, if a first or second nomination for the position has been submitted to the Senate for confirmation and is pending. The acting officer can continue to serve for an additional 210 days after the rejection, withdrawal, or return of such a nomination. Notably, the Supreme Court of the United States has held that a provision of the Vacancies Act limits the conditions under which an individual may serve in both an acting capacity and as the nominee to the same position. The court's opinion appears to allow an individual to serve on this basis only if the individual has served as the first assistant to the vacant position for more than 90 of the preceding 365 days or if the individual is serving as first assistant, and that position itself requires the advice and consent of the Senate. Temporary appointments to vacancies that exist during the 60-day period following the inauguration of a new President are treated differently, which gives the new President additional flexibility during the transition. The ordinary 210-day restriction period does not commence until the later of the following two dates: 90 days after the incoming President assumes office, or 90 days after the vacancy occurs. In general, once the time limitations of the Vacancies Act have been exhausted, only the head of the agency may perform any non-delegable function or duty of that office. Appointees under the Vacancies Act are authorized to "perform the functions and duties of the office temporarily in an acting capacity subject to [these] time limitations." The act does not apply to positions on multi-headed regulatory boards and commissions, or to new positions that have never been filled. The President's authority to make recess appointments is conferred by the Constitution, which states that "[t]he President shall have Power to fill up all Vacancies that may happen during the Recess of the Senate, by granting Commissions which shall expire at the End of their next Session." Presidents have made such appointments during within-session recesses ( intrasession recess appointments) and between sessions ( intersession recess appointments). Recess appointments expire at the end of the next session of the Senate. As a result, a recess appointment may last for less than a year, or nearly two years, depending on when the appointment is made. Presidents have occasionally used the recess appointment power in ways that have had the effect of circumventing the confirmation process. In response, Congress has placed restrictions on the President's authority to make recess appointments. Under 5 U.S.C. §5503(a), if the position to which the President makes a recess appointment falls vacant while the Senate is in session, the recess appointee may not be paid from the Treasury until he or she is confirmed by the Senate. The salary prohibition does not apply (1) if the vacancy arose within 30 days before the end of the session; (2) if a nomination for the office was pending when the Senate recessed, provided that the nominee was not previously recess appointed to the position; or (3) if a nomination was rejected within 30 days before the end of the session and another individual was given the recess appointment. A recess appointment falling under any one of these three exceptions must be followed by a nomination to the position not later than 40 days after the beginning of the next session of the Senate. For this reason, when a recess appointment is made, the President generally submits a new nomination for the nominee even when an old nomination is pending. In some instances, a recess appointee whose nomination to the position is not successful might not be paid. These instances are discussed below. (See " Unsuccessful Nominations and Payment Limitations .") From the 110 th Congress onward, it has become common for the Senate and House to use certain scheduling practices as a means of precluding the President from making recess appointments. The practices do this by preventing the occurrence of a Senate recess of sufficient length for the President to be able to use his recess appointment authority. These congressional scheduling practices might have prevented President George W. Bush from making recess appointments at the end of his presidency; he made no recess appointments during the times this approach was in use. It also might have limited use of the recess appointment power by President Obama. In January 2012, President Obama appeared to challenge the ability of this practice to prevent the exercise of his authority. He made four recess appointments during a three-day recess between pro forma sessions of the Senate on January 3 and January 6, 2012, a period that was generally considered too short to permit recess appointments. The recess during which the President made the appointments was part of a period of Senate absence that, but for the pro forma sessions, would have constituted an intrasession adjournment of 10 days or longer. In an opinion regarding the lawfulness of these appointments, the Office of Legal Counsel in the Department of Justice argued that "the President may determine that pro forma sessions at which no business is to be conducted do not interrupt a Senate recess for the purposes of the Recess Appointments Clause." The U.S. Supreme Court later concluded otherwise in a case regarding three of the four appointments. It held that, for purposes of the Clause, "the Senate is in session when it says it is, provided that, under its own rules, it retains the capacity to transact Senate business." The Court also held that the President may use the recess appointment power essentially only during a Senate recess of 10 days or longer. A Senate recess of 3 days "is not long enough to trigger the President's recess appointment power," and a recess of more than 3 days but less than 10 is "presumptively too short to fall within the Clause" but "leaves open the possibility that a very unusual circumstance could demand the exercise of the recess-appointment power during a shorter break." In some cases, Congress has expressly provided for the temporary filling of vacancies in a particular advice and consent position. Generally, such provisions employ one or more of several methods: (1) a specified official is automatically designated as acting; (2) a specified official is automatically designated as acting, unless the President provides otherwise; (3) the President designates an official to serve in an acting capacity; or (4) the head of the agency in which the vacancy exists designates an acting official. The top positions at the Office of Management and Budget (OMB), the Federal Aviation Administration (FAA), and the Small Business Administration (SBA), among others, are temporarily filled through the first method. For example, the U.S. Code provides that "[t]he Deputy Director [of OMB] acts as the Director when the Director is absent or unable to serve or when the office of Director is vacant." The relevant statute states that, at the FAA, the "Deputy Administrator acts for the Administrator when the Administrator is absent or unable to serve, or when the office of the Administrator is vacant." With regard to the SBA, federal law provides that the "Deputy Administrator shall be acting Administrator of the Administration during the absence or disability of the Administrator or in the event of a vacancy in the office of the Administrator." The top positions at the General Services Administration (GSA) and Social Security Administration (SSA) are temporarily filled through the second method above, in which a specified official is automatically designated as acting, unless the President provides otherwise. With regard to GSA, the "Deputy Administrator is Acting Administrator ... during the absence or disability of the Administrator and, unless the President designates another officer of the Federal Government, when the office of Administrator is vacant." Similarly, the "Deputy Commissioner [of SSA] shall be Acting Commissioner of the Administration during the absence or disability of the Commissioner and, unless the President designates another officer of the Government as Acting Commissioner, in the event of a vacancy in the office of the Commissioner." Positions for which the President is authorized to designate an acting official—the third method above—include the General Counsel at the National Labor Relations Board and the Special Counsel for Immigration-Related Unfair Employment Practices at the Department of Justice.