Eric Maskin and Amartya Sen in The NY Review of Books:
Americans have been using essentially the same rules to elect presidents since the beginning of the Republic. In the general election, each voter chooses one candidate; each state (with two current exceptions) awards all its Electoral College votes to the candidate chosen by the largest number of voters (not necessarily a majority) in that state; and the president-elect is the candidate with a majority of Electoral College votes.
Primary elections for president have also remained largely unchanged since they replaced dealings in a “smoke-filled room” as the principal method for selecting Democratic and Republican nominees. In each state, every voter votes for one candidate. In some states, the delegates to the national convention are all pledged to support the candidate getting a plurality of votes (again, possibly less than a majority). In others, delegates are assigned in proportion to the total votes of the candidates.
These rules are deeply flawed. For example, candidates A and B may each be more popular than C (in the sense that either would beat C in a head-to-head contest), but nevertheless each may lose to C if they both run. The system therefore fails to reflect voters’ preferences adequately. It also aggravates political polarization, gives citizens too few political options, and makes candidates spend most of their campaign time seeking voters in swing states rather than addressing the country at large.
There are several remedies. Perhaps in order of increasing chance of adoption, they are: (1) to elect the president by the national popular vote instead of the Electoral College; (2) to choose the winner in the general election according to the preferences of a majority of voters rather than a mere plurality, either nationally or by state; and, easiest of all, (3) to substitute majority for plurality rule in state primaries.