(b)
The President, at any time in the public interest, may—
(1)
except an agency or part thereof, or an employee or group or class of employees therein, from this chapter or a provision thereof (except this section); and
(2)
withdraw an exception made under this subsection.
However, the President may not except the Office of Personnel Management from a provision of this chapter which vests in or imposes on the Office a function, duty, or responsibility concerning any matter except the establishment, operation, and maintenance, in the same capacity as other agencies, of training programs and plans for its employees.