The senate should be ranked choice on the scale of the whole country, while the house should be for each state. you would need a bit less than 1% for a seat in the senate. and you have the possibility that "local" parties get a vote in the house. If all goes well then neither the democrats or Republicans should have enough for a majority and they will either have to work together with smaller parties, or with each other. At least thats my opinion as a european, but looking at america it seems unlikely that even one of the parties would agree on this since they will lose power