Notwithstanding
section 1009(e) of this title, an agency may nominate either a person from the Federal Government or a person from outside the Federal Government to serve as a facilitator for the negotiations of the committee, subject to the approval of the committee by consensus. If the committee does not approve the nominee of the agency for facilitator, the agency shall submit a substitute nomination. If a committee does not approve any nominee of the agency for facilitator, the committee shall select by consensus a person to serve as facilitator. A person designated to represent the agency in substantive issues may not serve as facilitator or otherwise chair the committee.