[lordnacho]

It's a big piece of it, seemingly.

The US has an interesting constitution:

- First past the post. Such systems tend to favour fewer parties. The UK (also FPTP) barely has more than two parties. In most of continental western europe, there's considerably more, due to proportional representation. On the continent you end up having a bunch of different opinions, and you don't have to squish every issue onto a liberal/conservative axis. For instance you get socially conservative big state parties. Or socially liberal big state parties. Or socially liberal small state. And there's other axes too.

- A separate executive. In the UK even though they have FPTP, they have a government formed by the leader of one of the parties, and they "whip" the MPs to vote according to the party line, subject to various forms of sanction depending on how important an issue is. In the US, you choose two legislatures and a separate president. If they're not in agreement, it de facto entrenches the existing status quo by making it hard to change the law.

[joveian]

I think the seperate executive could be more a strength than a weakness in that it could allow a congressional system where stable coalitions are unnecessary and different issues could result in different coalitions. Possibly this happens more than I would think in systems that require coalitions, but it seems to me like not needing them would be more likely to change the simplistic us vs them narrative.

The other issue is which system to change to. There doesn't seem to be a single ideal system. IMO, in terms of the voting itself, ability to resolve an election in one ballot, limiting the usefulness of strategic voting, and getting at least close to a Condorcet winner would be the most useful properties.

I recently started to try to put together something based on five value range voting but I'm not sure it is even possible to derive a system from that which has the above properties. I haven't found any existing methods that seem to fit the above properties well, although some are much closer than others. Another option, easier in a lot of ways but more expensive, would be two ballot elections.

There is also the structural part. IMO, a parallel system has more appeal than mixed member proprotional, but it has some significant disadvantages as well. Anytime a significant change is proposed there will be strategic maneuvering for a system that benefits particular interests.

As someone else mentioned, states need to change first. The west coast in general would be a great place for that and I think Oregon may be taking the lead in political disfunction at this point (well, on the west coast at least, even though California is very innovative in that area)...