If I were your opponent, the main question I would ask is "what about freedom of speech?" I would ask how you can reconcile the idea of freedom of speech with the idea of telling people that they can only use federal money to fund their campaigns? What if I want to spend a lot of my money on my campaign? What if my friends want to spend money to help me? If you tell us we can't, aren't you infringing on our freedom of speech?
The question I would ask my opponent is "doesn't it hurt our democracy when money has such a huge impact on elections? I would ask what my opponent thinks donors expect when they give money. Won't they expect politicians to do favors for them or at least listen to them whenever they want to be heard? Won't the politicians feel they need to suck up to those donors so that the donors will give them money for their next election?
Those are the two main issues for and against on this topic.