An adversarial negotiation style is appropriate when one party has high bargaining power and is focused on maximizing its benefit rather than maintaining a long-term relationship. This approach often involves competitive tactics that leverage power disparities, aligning with CIPS guidance on when adversarial tactics may be strategically used in negotiations.

Commercial negotiations involve a wider set of stakeholders than procurement, budget holders, and users.
Depending on context, directors, IT specialists, legal teams, regulators, or external partners may all be impacted. Ignoring them risks resistance or missed requirements. CIPS stresses stakeholder mapping tools (such as Mendelow's Matrix) to identify influence and interest levels, ensuring all relevant parties are managed appropriately in negotiation preparation and execution. Narrow stakeholder identification can undermine outcomes.
Reference: CIPS L4M5 (2nd ed.), LO 3.1 - Stakeholder identification and management in negotiations.

In the scenario, to exchange cost cutting, the purchasing manager promises to 'reward' supplier shorter payment period. This is an example of reward power, which results from one person's ability to compensate or reward another for compliance.
The reward does not need to be money, but could be introduction to other buyers in the group, positive references, agreement to trial new product, quicker payment or indeed any other variable that the buyer knows is attractive and valued by the supplier.

A perfectly competitive market is one with the following features:
- There are many firms producing identical or very similar (homogeneous) goods or services
- There are no barriers to entry to the market or exit from the market - anyone can enter or leave easily
- Both producers and customers have perfect knowledge of the market place, prices, costs of production and influences on demand and supply Under these conditions, the price and quantity will always tend toward equilibrium as any producer that sets a price above equilibrium will not sell anything at all, and any producer that sets a price below a equilibrium will obtain 100% market share in theory. The demand curve is perfectly elastic, which means that it will be horizontal. In a perfectly competitive market, it is difficult to increase profits through pricing, and suppliers instead must focus on their cost structure. As these conditions imply, there are few if any examples of perfectly competitive market.
LO 2, AC 2.2

Essential goods and services such as electricity, fuel, basic food stuffs, commuter transport and habitual products such as tobacco, alcohol and sugar-based drinks are often sited as facing a relatively inelastic demand curve. This means when the price goes up, the quantity demanded does not decrease very much and so they are often the target of government taxation.
LO2, AC 2.2