Hearings may be public and may be held before the Commission, any member or members thereof, or any officer or officers of the Commission designated by it, and appropriate records thereof shall be kept. In any proceeding before the Commission, the Commission, in accordance with such rules and regulations as it may prescribe, shall admit as a party any interested State, State commission, State securities commission, municipality, or other political subdivision of a State, and may admit as a party any representative of interested consumers or security holders, or any other person whose participation in the proceedings may be in the public interest or for the protection of investors or consumers