What is the contracting method that allows solicitation for proposals, both competitively and non-competitively?

The contracting method that permits the solicitation of proposals through both competitive and non-competitive means is negotiation. This approach is versatile and allows agencies to engage in discussions and modifications with offerors to reach the best possible agreement. By using negotiation, contracting officers can tailor their approach based on the specific needs and circumstances of the procurement, thereby accommodating a variety of proposal types and allowing for flexibility in discussions.

In contrast, methods such as sealed bidding are generally restricted to competitive processes, where bids are submitted in a fixed format and opened publicly, preventing negotiation. Single-source negotiation is limited to cases where there is only one provider of a good or service, and while it involves negotiation, it does not encompass competitive solicitation. Two-step sealed bidding combines elements of both sealed bidding and negotiation but typically does not allow for general negotiation in the same way as a straightforward negotiation process would.