Consultants tell candidates how to talk, what to wear, how to stand, what to say, etc. Propaganda is taken from the Latin word propagane, referring to a gardener's practice of putting fresh roots in the earth to reproduce new plants. The Catholic church established the College of Propaganda in 1622 to propagate the Christian religion. Persuasion is propaganda Communication of information is education. Some crossover either way.
Most communication has some end in mind, some purpose.
Expressing yourself is a basic human right. We have a right to a point of view, a different point of view from others. Public relations as a profession developed to help clients get their point of view expressed, using the mass media, in a crowded public forum and over long distances. Public relations is a profession devoted to getting one group to see the world as another group sees it. You could argue that public relations is necessary, in a democracy, because nothing succeeds without the approval of the people.