Why do people follow you as a leader? If you can answer that question, then you know where you get the power to lead. Positional authority is still needed at times because of the demands of the situation. Many other times, relational capital is far more important and all that is available. This post by Brett Powell is worth the read:
“What gives you the power to lead? Ministry leaders have little authority over their people. In other organizations, the person who has a leadership position has incredible leverage to get people to do what they want them to. In business for example, managers have leverage in the form of salary, benefits, and perks. Most followers are pretty cooperative when their livelihood is at stake.”