§ 3029. Temporary appointments and promotions generally
(a)
Ensign
Temporary appointments in the grade of ensign may be made by the President alone. Each such temporary appointment terminates at the close of the next regular session of the Congress unless the Senate sooner gives its advice and consent to the appointment.
(b)
Lieutenant (junior grade)
Officers in the permanent grade of ensign may be temporarily promoted to and appointed in the grade of lieutenant (junior grade) by the President alone whenever vacancies exist in higher grades.
(c)
Any one grade
When determined by the Secretary to be in the best interest of the service, officers in any permanent grade may be temporarily promoted one grade by the President alone. Any such temporary promotion terminates upon the transfer of the officer to a new assignment.