This paper studies negotiations between two parties whose political power changes over time. The model has a unique subgame perfect equilibrium, which becomes very tractable when parties can make offers frequently. This tractability facilitates studying how changes in political power affect implemented policies. An extension of the model analyses how elections influence inter-party negotiations when implemented policies affect the parties' political power. Long periods of gridlock may arise when the time left until the election is short and parties have similar levels of political power.