Scott Mainwaring (Notre Dame) and Lee Drutman (senior fellow at New America) have this new whitepaper at Protect Democracy, “The Case for Multiparty Presidentialism in the U.S.“:

For many Americans, anything besides our two-party electoral system is hard to imagine. Multiple parties and proportional representation, the main alternative, might seem more fitting for a parliamentary system than our presidential one. But the truth is, how a country elects its legislature and how it selects its executive are two separate decisions. Multiparty presidentialism — the system the United States would have if it adopted proportional representation — is common around the world.