Uruguay’s leftist opposition candidate, Yamandú Orsi, claimed victory in a tight presidential runoff Sunday, ousting the conservative governing coalition and making the South American nation the latest to rebuke the incumbent party in a year of landmark elections.

The candidate of the conservative coalition that has governed for the past five years conceded defeat after a tight runoff, as Uruguay joined others around the world in rebuking the incumbent party in a year of landmark elections.

Mr. Delgado’s concession signaled an end to the short stint of the right-leaning government in Uruguay that in 2020, when President Luis Lacalle Pou took office, ended 15 years of government by the Broad Front. During that period, the Broad Front oversaw the legalization of abortion, same-sex marriage and the sale of marijuana.