“ No individual who is serving in an office listed in section 2 (a) - (k) in an acting capacity, by virtue of so serving, shall act as Administrator pursuant to this order. (b) Notwithstanding the provisions of this order, the President retains discretion, to the extent permitted by the Federal Vacancies Reform Act of 1998, 5 U.S.C. 3345 et seq., to depart from this order in designating an acting Administrator. ”