An alternative to "first past the post"; it's used in US politics. If a primary election fails to produce a victor surpassing a certain threshold of votes, the top two candidates square off again, to produce a winner. Traditionally, that threshold has been 50% of the vote, but, in some locales, it has been reduced to 40%, making it slightly easier for minority or third-party candidates (in the case of "open primaries") to win.