I had a thought that may, or not, work. What would happen if a state declared that their elections, even for federal office, are basically local. That being the case the state will no longer allow money, from outside of the state, to be spent on ANY state election. As such money would be taken, by the state, and added to a state election fund to be spent on those campaigns that are being properly funded from funds provided within the state itself.
Funds from inside the state must be earned within the state to qualify. Multi-state companies who provide funds for campaigns must prove such funds were earned within the state.
I have no idea if this would even be legal but it would, if nothing else, point out any number of things to that minority of voters that actually vote (last November we were gifted with 37% actually voting). In addition to that I suspect that such a thing would stir up the entire United States election/campaign thing thereby providing that which politics are famous - entertainment!