What is the most important attribute of a Project Manager?

I think that one of the skills that serves a Project Manager the most of the ability to be a diplomat. Often a Project Manager will find themselves in a situation (sometimes hostile) where they need to obtain resources, skills and knowledge from those that often have different vested interests from= the objectives of the project. The skills of patiently negotiating and sometimes cajoling to help achieve that which they need to ensure the success of the project is critical. Sometimes the diplomacy needs to have a certain steeliness of purpose to ensure that the Project Manager can get what they need and the tenacity to persevere to help ensure delivery is an essential characteristic of a successful project manager.