Temporary appointments in the grade of ensign, lieutenant junior grade, or lieutenant may be made by the President.

A temporary appointment to a position under subsection (a) shall terminate upon approval of a permanent appointment for such position made by the President.

Appointees under subsection (a) shall take precedence in the grade to which appointed in accordance with the dates of their appointments as officers in such grade. The order of precedence of appointees who are appointed on the same date shall be determined by the Secretary.

When determined by the Secretary to be in the best interest of the commissioned officer corps of the Administration, officers in any permanent grade may be temporarily promoted one grade by the President. Any such temporary promotion terminates upon the transfer of the officer to a new assignment.