This paper presents a novel dynamic bargaining game where every party is proposing only its own contribution, before all pledges must be unanimously approved. I show that, with uncertain tolerance for delay, each equilibrium pledge maximizes an asymmetric Nash product. The weights on others' payoffs increase in the uncertainty, but decrease in the correlation of the shocks. The weights vary pledge to pledge, and this implies that the outcome is generically inefficient. The Nash demand game and its mapping to the Nash bargaining solution follow as a limiting case. The model sheds light on the Paris climate change agreement, but it also applies to negotiations between policymakers or business partners that have differentiated responsibilities or expertise.