If you do not answer the application will become abandoned. I do not understand why you cannot answer the OA in view of the negotiations but that may be irrelevant. Once it becomes abandoned you have two months to petition to revive the abandoned application.
You should have a TM attorney take care of responding to the OA as it may affect the negotiations.
USPTO Registered Patent Attorney, Master of Intellectual Property law, MBA I am neither your attorney, nor my answers or comments in AVVO.com create an attorney-client relationship with you. You may accept or disregard my free advice in AVVO.com at your own risk. I am a Patent Attorney, admitted to the USPTO and to the Florida Bar.
Attorney Golab's answer is right on point.
I would add that the Trademark Examining Attorney is mandated to scrutinize the terms of whatever agreement you file with the Office and determine whether it fulfills the principle of "consumer protection" that's behind U.S. trademark law. If you aren't already being advised on this project by an attorney experienced in trademark matters, you might find that all this effort turns out just to be spinning your wheels.
This posting is intended for general education and isn't "legal advice." It doesn't create or evidence an attorney-client relationship. You are encouraged to engage an attorney in the pertinent jurisdiction for confidential legal advice on matters of any importance.
It sounds like you are handling both the trademark application and the consent agreement without counsel. This is a very bad idea. You need to provide a meaningful substantive response to the office action on time, and you would be making a potentially disastrous mistake by working out a consent agreement without counsel. From the point of view of the trademark office, you have had more than sufficient time to answer the office action and you will not get very far merely by putting in a response stating that you are working on a consent agreement--such a response may be the equivalent of abandonment.