The United States is unique among democracies for the durability of its two-party system. Why in this context does electoral “reform” ever succeed?
My post at Matthew Shugart’s Fruits and Votes lays out a model and applies it to the ranked-choice voting win in Maine. The theory is built to account for the spread of proportional representation (PR) in US cities, 1915-48. I suspect (and hope) it applies more broadly. The key elements are: a “reform” template, a losing party, and ruling-party factionalism.
The theory comes from my article on American PR adoptions, now online at American Politics Research.