Conservative candidate Alvaro Noboa has maintained his lead in the latest count of Ecuador's presidential poll.
The latest results put the two candidates almost neck and neck
With 87.5% of the votes now counted, the electoral authorities gave Mr Noboa 26.3% of the ballots to 23.2% for closest rival Rafael Correa.
Initial results showed the left-wing candidate ahead by a narrow margin. Mr Correa has claimed electoral fraud.
Police have raided the office of the Brazilian company hired to speed-count the results after its system collapsed.
The general attorney's office is investigating alleged irregularities in the process, which the company, E-vote, denies.
Neither candidate looks set to gain the necessary 40% to win outright, forcing a second round run-off next month.
Mr Correa has said Sunday's vote was marred by fraud, but election monitors from the Organization of American States say they have found no irregularities.
According to an earlier preliminary count of 72% of the ballots carried out by E-vote, Mr Noboa had 26.7% of the vote and Mr Correa 22.5%.
The election has been marred by allegations of fraud
The findings were rejected by Mr Correa - a former economy minister - who said his exit polls suggested that it was he who enjoyed a slight lead.
On Monday, some of Mr Correa's supporters gathered outside the electoral tribunal, accusing E-vote and the country's electoral authorities of fraud.
They were joined by supporters of some of the other 11 candidates, who were angry about the delay in the counting process.
The head of the electoral tribunal, Xavier Cazar, dismissed claims of fraud in the "quick count", saying the results matched exit polls conducted by the media.
Under Ecuadorean law, the electoral authorities have 10 days to present the official results.
The BBC's Daniel Schweimler in the capital, Quito, says the two contenders represent the two sides of a divided country.
Mr Noboa - Ecuador's richest man - enjoys much of his support in Ecuador's financial centre, the coastal city of Guayaquil, while his left-wing opponent is popular among the country's rural poor, and in Quito.
Many people in Ecuador are already disillusioned with their politicians, our correspondent says.
The fight between Mr Correa and Mr Noboa is likely to be aggressive and is unlikely to restore much faith in the country's politicians, analysts say.
Popular protests drove the last three elected presidents from power, and only three since 1979 have succeeded in serving full terms.