In the US, the party list would likely be chosen by party primaries (i.e. voters) rather than the party. That would largely negate the first problem. Similarly

In the US, the party list would likely be chosen by party primaries (i.e. voters) rather than the party. That would largely negate the first problem. Similarly, for the second, the US has two very strong political parties and this would really only change House of Representatives (one portion of one branch of the federal government) so the kingmaking power would be extremely limited as the vast majority of the Senate & Presidency would still end up with the stronger parties.