What if the United Kingdom and the United States had adopted the following Electoral System at some point during the Twentieth or Twenty-First Century?
In this system, single member constituencies/electoral districts exist just like under FPTP. The difference is that if no candidate receives more than 50% of the vote, negotiations followed by an agreement between candidates who have at least 50% of the vote between them then have to occur. For example, should a candidate from party X come first in the race, but only get 42% of the vote, he will need to obtain the support from a fellow candidate in the race (Candidate Y) who has himself received more than 8% of the vote in order to be over the 50% line and become the MP. It doesn't end there however since at any time during the subsequent parliamentary term, if Y feels that X, as MP, has not been delivering on the promises that he agreed to in the negotiations, Y can withdraw his support for X and unless someone else with at least 8% of the vote from the last election can agree to support X, or another candidate can be agreed upon with enough votes between him and someone else, then a by-election has to occur and it starts again from there.
The system would be the same for Presidential races in the United States.
What do you think the consequences would be like for Politics in both the United Kingdom and the United States?