21. Subject to the conditions specified in the call for tenders and in accordance with its express provisions concerning how it may be amended, the public body may,(1) after the first stage of the selection process and at any subsequent stage, undertake discussions with each of the selected tenderers to further define the technical, financial or contractual aspects of the project and give each of them the opportunity to submit a proposal based on the outcome of those discussions; and
(2) at the end of the selection process, negotiate, with the selected contractor, the provisions needed to finalize the contract while preserving the basic elements of the tender documents and the proposal.