Former Wall Street executive Pedro Pablo Kuczynski's lead over Keiko Fujimori, the daughter of an imprisoned former authoritarian leader, narrowed to just 0.36 percentage points late Monday.
With 95 percent of votes processed in Peru's closest presidential election in at least 50 years, Kuczynski led Fujimori by fewer than 60,000 votes. Preliminary results Sunday put more than a percentage point between them.
Votes from Peruvians living abroad, which had largely still to be tallied, could decide the outcome. One review of sample ballots suggested they were more likely to favor Kuczynski, a former prime minister and World Bank economist.