Undecided Question

Who should I target in my argument essay?

I am writing an argument essay for my comp 2 class. I am arguing that therapeutic cloning (the cloning of stem cells NOT the cloning of humans) should be allowed because it has the potential to cure many diseases. My audience needs to be either a group of people or a specific person, preferably someone who would oppose my argument. I also need to state which format I would use. For example, if my audience was Obama, my format would be a letter. Since President Obama is already for therapeutic cloning, I need a different audience and format. Who can I target, and in what form should my essay be?