In your presentation you need to clearly communicate that you have reviewed the background research literature. You also need to explain how what you propose will advance what is already known about the subject. An approach that works for many students is to present the literature review in the “funnel-down” approach. Begin with material that talks about your topic broadly and emphasizes its significance, and then gradually bring the focus down to what you are going to study. For example, you might say, "Credibility is an important concept in communication that is related to a speaker’s effectiveness. Credibility is a crucial factor in presidential campaigns. Therefore, the research I propose will be an examination of the role of candidate credibility in the 2008 U.S. presidential campaign."
Your presentation must convince your committee that your research is appropriate in size and scope and represents an original contribution to the field, A responsible committee will save you from yourself if you propose a project it thinks will be too large to complete. Alternately, the project must be big enough to warrant awarding you a Ph.D. for completing it. If your project is the type that requires you to gain access to particular people or already existing data, your proposed means of access should be included in the proposal presentation. If you have letters confirming your access, be sure they're in the proposal and your committee knows it.
Whatever your research, it is up to you to convince your committee that the way you propose to approach your subject matter is a good one. It needn’t be the only one, but it must be at least one good way to address your research questions or hypotheses. Tell the committee what sources you will be analyzing and comparing. If sampling is involved, tell them how you will be sampling. Detail your plans for analyzing your data. Be clear and succinct. The more convinced the committee is that you know what you are doing, the more likely you are to receive its approval, and the more you include in your proposal, the farther along you will be with your project. If the committee agrees to the proposal, it will have agreed to your proposed procedures and methodology.