Peru’s leftist presidential candidate Roberto Sanchez said on Tuesday he would not recognise the result of the country’s presidential runoff, alleging fraud as his conservative rival Keiko Fujimori held a narrow lead.

The declaration raises the prospect of a prolonged political crisis in Peru as the country awaits a final result in one of the closest presidential races in its history.

At a press conference, Sanchez said “fraud is underway” in a process he said was favouring Fujimori. Electoral authorities have been reviewing contested ballots from the June 7 runoff for weeks, with Fujimori leading 50.11% to 49.89%.

“We believe there’s been a manipulation of the vote,” Sanchez said, accusing Peru’s ONPE electoral authority and Fujimori’s campaign of irregularities in the votes cast abroad, which heavily favoured Fujimori.

“We will not recognize Fujimori’s government,” Sanchez said. He has urged his supporters into the streets and called for further marches on Saturday.

The ONPE, Peru’s national electoral jury (JNE) and Fujimori’s campaign did not immediately respond to a request for comment.

Sanchez’s party, Together for Peru, won the second-largest number of seats in Congress, securing 32 of the 130 seats in the lower house and 14 of 60 seats in the Senate.

Fujimori’s party will have the largest congressional bloc, with 22 Senate seats and 41 in the lower house. Fujimori, the daughter of late former President Alberto Fujimori, is making her fourth bid for the presidency.

Sanchez led the race earlier as rural votes were counted, but Fujimori closed the gap as ballots cast overseas began to be processed.

With such a tight race, both candidates had refrained from claiming victory or conceding defeat until 100% of the vote had been counted. After weeks of reviewing contested ballots, 99.72% of the total vote has been counted as of early Tuesday.

(Reporting by Marco Aquino; Writing by Alexander Villegas; Editing by Franklin Paul and Sanjeev Miglani)