Persuasion is a common social and economic activity. It usually arises when conflicting interests among agents exist, and one of the agents wishes to sway the opinions of others. This paper considers the problem of an automated agent that needs to influence the decision of a group of self-interested agents that must reach an agreement on a joint action. For example, consider an automated agent that aims to reduce the energy consumption of a nonresidential building, by convincing a group of people who share an office to agree on an economy mode of the air-conditioning and low light intensity. In this paper we present four problems that address issues of minimality and safety of the persuasion process. We discuss the relationships to similar problems from social choice, and show that if the agents are using Plurality or Veto as their voting rule all of our problems are in P. We also show that with K-Approval, Bucklin and Borda voting rules some problems become intractable. We thus present heuristics for efficient persuasion with Borda, and evaluate them through simulations.