Answer: The purpose that a political persuasive speech might serve is to convince the public to support an idea.
Step-by-step explanation: A persuasive speech intends to influence an audience's point of view. In that way, politicians generally give persuasive speeches to convince their public to do something or adopt a particular point of view. Moreover, when delivering a political persuasive speech, the speaker also resorts to pathos, which consists in an appeal to the audience's emotions. However, although pathos prevails, the other two modes of persuasion, ethos and logos, can also be present in a political persuasive speech in order for the speaker to achieve his/her aim: convincing his public to support certain ideas.