When 18 million votes were counted, the situation was so even between the two candidates that no winner could yet be declared.
The election is between leftist candidate Roberto Sánchez and right-wing populist Keiko Fujimori. With 94 percent of the votes counted on Monday night, Sánchez had a narrow lead of less than 3,000 votes. At that time, each candidate had held the lead at different points in the count.
Keiko Fujimori is making her fourth attempt to become president. She is the daughter of authoritarian former President Alberto Fujimori, who was deposed and imprisoned.
Psychologist Roberto Sánchez, who is running for the third time, is accused of irregularities in party contributions and could face trial.
The winner will become Peru's ninth president in a ten-year span.
