A campaign leader is a person engaged in various sectors. A campaign manager can organize and run a marketing campaign, for example, but these are often people who run the election campaign for politicians. Their role is one of the key ones, and their engagement can bring victory in elections. These are people who are well acquainted with public opinion and the situation in society.
Their methods were likely aggressive and they did anything they could to get what they wanted. I doubt their methods were very effective, but they may have had an effect over time.