Where time, the nature of the proceeding, and the public interest permit, all interested parties shall have the opportunity for submission to and consideration by the presiding officer of offers of settlement, or proposals of adjustment together with facts and/or arguments relevant to such offers or proposals without prejudice to the rights of the parties. The presiding officer need not be present at any negotiations of such nature. The presiding officer shall issue an initial or recommended decision thereon recommending approval or disapproval of such offer of settlement or proposal of adjustment to the Administration for final action thereon. No agreement, offer, or proposal shall be admissible in evidence over the objection of any party in any hearing on the matter. When any settlement does not dispose of the whole proceeding, the remaining issues shall be determined in accordance with sections 7 and 8 of the Administrative Procedure Act.