The Secretary may employ a staff in accordance with the State budget. Each staff assistant in charge of a particular area of responsibility and each professional consultant is in the executive service, management service, or is a special appointment in the State Personnel Management System and is appointed by and serves at the pleasure of the Secretary. Except as provided in subsection (b) of this section or otherwise by law, the Secretary shall appoint and remove all other staff in accordance with the provisions of the State Personnel and Pensions Article. The Secretary may review any personnel action taken by any unit in the Department. The appointment or removal of personnel by a board, division, or other agency within the jurisdiction of the Department is subject to the approval of the Secretary. The Secretary may delegate the power of approval to the heads or governing bodies of the boards, commissions, divisions, or other agencies within the jurisdiction of the Department.