Your thesis statement is the central argument of your essay. It must be concise and well-written. Your thesis goes in the introductory paragraph. Don't hide it; make it clearly asserted at the beginning of your paper. Your thesis must make an argument. It is the road map to the argument you will subsequently develop in your paper. Thesis statements must make a claim or argument. They are not statements of fact. Statement of fact: "A candidates ability to afford television advertising can have an impact on the outcome of Congressional elections." This is essentially an indisputable point and therefore, not a thesis statement. Similarly, the claim "The United Nations was established to promote diplomacy between major powers." is not likely to inspire much debate.