Why did Salvador Allende win Chile’s presidency in 1970 without receiving a majority of the popular vote?

In the 1970 Chilean presidential election, Salvador Allende led a three-way race with 36.3 percent of the popular vote. Because he did not secure an absolute majority (more than 50 percent), the Chilean constitution required the National Congress to choose between the two leading candidates.12

Although it was customary for Congress to select the candidate who received the most votes, Allende faced significant opposition from right-wing factions. His election was ultimately confirmed by Congress on October 24, 1970, after he agreed to support 10 libertarian constitutional amendments demanded by the Christian Democrats. This confirmation occurred despite covert efforts by the United States to prevent his presidency, including attempts to bribe members of Congress and organize a military coup.12