A negotiation can consume weeks and still leave no acceptable proposal. That effort is already spent. Accepting unsuitable future work does not recover it.

For an unaccepted proposal, compare the whole package with your current alternative and minimum requirements. Check that the alternative remains available and that your earlier estimate still fits the facts. A lower price with a smaller scope is not the same proposal as a price cut alone.

Declining a new proposal is different from ending an existing commitment. Establish which situation you are in before treating “walk away” as an available action.