Peru’s electoral authorities began reviewing thousands of contested ballots on Monday, stalling the count in the April 12 general election and delaying final results, as no clear presidential rival has emerged to face conservative frontrunner Keiko Fujimori in a June runoff.

Roughly 6% of polling stations – representing more than one million votes – were challenged last week due to inconsistencies, missing information or errors on tally sheets, according to Peru’s National Office of Electoral Processes (ONPE).

Peru’s top electoral body, the National Jury of Elections (JNE), said it has started reviewing disputed polling stations in public hearings before adding them to the final tally, a process that could take weeks.

The final result of the presidential election will be known no later than May 15, legal coordinator for the JNE, Jorge Valdivia, told a press conference on Monday.

“That is the latest date we have set, because time must be given to the candidates who advance to the runoff to carry out their campaign activities,” Valdivia said.