There shall be a general counsel of the board who shall be appointed by the Governor, subject to confirmation by a majority of the Senate, for a term of four years. The general counsel shall have the power to appoint such attorneys, administrative assistants, and other employees as necessary for the proper exercise of his duties. The general counsel of the board shall exercise general supervision over all attorneys employed by the board (other than administrative law officers and legal assistants to board members), and over the officers and employees in the regional offices. He shall have final authority, on behalf of the board, with respect to the investigation of charges and issuance of complaints under Chapter 6 (commencing with Section 1160) of this part, and with respect to the prosecution of such complaints before the board. He shall have such other duties as the board may prescribe or as may be provided by law. All employees appointed by the general counsel shall perform their duties in an objective and impartial manner without prejudice toward any party subject to the jurisdiction of the board. In case of a vacancy in the office of the general counsel, the Governor is authorized to designate the officer or employee who shall act as general counsel during such vacancy, but no person or persons so designated shall so act either (1) for more than 40 days when the Legislature is in session unless a nomination to fill such vacancy shall have been submitted to the Senate, or (2) after the adjournment sine die of the session of the Senate in which such nomination was submitted.