(Reuters) --- Peruvian socialist Pedro Castillo was holding on to a slim lead in the deeply divided country's presidential election on Wednesday with almost all votes processed, though with a gap of just 70,000, contested ballots could still be decisive.
Castillo, the son of illiterate farmers who has rattled the Andean nation's political elite and garnered huge support from the rural poor, had 50.2% with 99.8% of votes processed, just 0.4% percentage point ahead of right-wing rival Keiko Fujimori.
The tally is, however, preliminary because about 300,000 votes have been contested, which will need to be further scrutinized by an electoral jury, a process that will take several days to complete and could tip the balance.
Fujimori has held out hope of clawing back a win and an official from her party told Peruvian radio they were preparing with lawyers to demonstrate unsubstantiated allegations she had made saying that supporters of Castillo tried to steal votes.
"Today we are presenting all the evidence of irregularities," said Luis Galarreta, the vice presidential candidate on Fujimori's ticket.
Castillo's party have denied the claims and experts and international electoral observers have said that Peru's election was carried out cleanly.
Still, Fujimori's allegations could trigger days of confusion and tension, amid a polarized election cycle that has divided Peruvians, with higher-income citizens supporting the right-wing candidate and lower-income ones supporting Castillo.
On Tuesday, hundreds of voters on both sides demonstrated in front of Peru's elections office against the perception of irregularities in the vote counting process.
'TIGHTEST ELECTIONS'
Fujimori had closed the gap slightly overnight as almost all the overseas votes that favor the conservative candidate came in, though not by enough to rein in Castillo's lead as she had hoped, leaving disputed votes as her last potential reprieve.
"It's unlikely that at this point that Fujimori will overtake Castillo," said David Sulmont, a sociology professor at Peru's Pontifical Catholic University and former head of their polling unit.
"It is one of the country's tightest elections," he added. "The margin may keep varying, but I think Castillo will be the winner."
A win for Castillo, a teacher who was the surprise victor in the first-round vote in April, would mark a major advance for Latin America's left amid rising discontent over poverty and inequality that has been sharpened by the COVID-19 pandemic.
On Tuesday evening, Castillo came close to claiming victory. "We already have the official party tally, where the people have won this fight," he told supporters, referring to an unofficial vote count conducted by his party, Free Peru.
Fujimori is on her third attempt to become president, having been the runner-up in the last two cycles. In 2016, she lost by a margin of 0.24 of a percentage point.
Castillo has spooked markets with proposals to redistribute mining wealth, redraft the constitution and raise taxes on mining firms, a key source of revenue for the Andean country, though he has looked to moderate his tone in recent days.
