Federal Vacancies Reform Act of 1998
The Federal Vacancies Reform Act of 1998 (commonly called the Vacancies Act) (5 U.S.C. § 3345 et seq.) is a United States federal statute establishing the procedure for filling vacancies in an appointed office of an executive agency of the government before the appointment of a permanent replacement. The Act allows an incoming President 300 days in which to temporarily and unilaterally fill positions with "acting" officers.
Source: Wikipedia — Federal Vacancies Reform Act of 1998 (CC BY-SA 4.0)