An idiomatic term that describes, in  the context of negotiations, a source/ factor of influence or power that can be used (as a concession or inducement) by one party to persuade another party to act in a beneficial manner towards the fulfillment of a deal or agreement. Bargaining chips are used as leverage in negotiations relating to business or political situations, among others.

Examples:

• In their negotiation with management, the workers threatened to stage a strike during the busy season as a bargaining chip.
• Environmental activists used the vast damage caused by the latest nuclear catastrophe as a bargaining chip ahead of nuclear talks.