The cons of this proposal strongly outweigh the pros.
On the pro side, such a reform would presumably keep “too much” money from flowing into campaigns. It would ensure that campaigns for Congress would be funded by the people who are represented by a given member of Congress. However, there are many cons to this. First, it would likely be found unconstitutional. It would be an infringement on the free speech of other people in the country. Second, and more importantly, we have to remember that the vote of any individual representative can have an impact on the whole nation. Since each representative can impact the whole nation, it makes sense to allow the whole nation to contribute to their campaigns. Thus, the biggest “con” would be that this reform would prevent people from contributing to races that affect their lives.