The electoral council says the final result won't be possible until Wednesday as votes continue trickling in from isolated areas and from Ecuadorians abroad.
Ecuador's leftist government candidate Lenin Moreno looked set for victory in the presidential election, but a delay in results meant it may take days to know if he will face a runoff with former banker Guillermo Lasso.
The delay has sparked protests in some of Ecuador's biggest cities.
In a nail biter vote with eight candidates at the weekend, Moreno was close to the threshold needed to avoid a second round on April 2 and continue a decade-long period of leftist rule, just as South America is moving to the right.
TRT World spoke to Ecuadorian journalist Carolina Loza Leon who said, "The delay of the result created a lack of trust in an already contested elections. Many people are afraid that possible fraud could take place and this has caused people to go into the streets to demand the second round which is highly likely at this point."
While Ecuadorians are angry over an economic downturn and corruption scandals, the opposition split its votes among candidates and the ruling Country Alliance party remains popular with many poor voters thanks to social welfare programmes.
As results trickled in from isolated areas in the Andes, remote jungle villages and the Pacific coast, Moreno, a disabled former vice president, was just short of the 40 percent of votes and a 10 percentage-point difference over his nearest rival to win outright.
The electoral council said the clarity would not arrive for three more days due to votes trickling in from isolated areas and Ecuadorians abroad, bureaucratic delays and "inconsistencies" in some ballots.
"This doesn't smell right. How can they take three days to count 12 percent?" said Lasso, 61, who already celebrated reaching the second round in his humid hometown of Guayaquil under a stream of confetti on Sunday night.
"We're not going to allow fraud ... If they toy with the results, we'll take to the streets," he added.
Moreno shot down the opposition's stance.
"You can't be a sore loser," he told a news conference earlier on Monday.
"It's striking to me that there is a politician out there calling for violence," Moreno added, emphasising the need to wait for final results.
Meanwhile, a couple of hundred opposition supporters congregated in front of the electoral council headquarters in Quito to demand a speedier and more transparent count.
Some protesters waving Ecuadorian flags chanted slogans including "We're not Cuba or Venezuela, out with Correa!"
Outgoing President Rafael Correa was one of the key figures in Latin America's leftist axis that includes Caracas and Havana.
He brought stability to the politically turbulent petroleum exporting country, but has aggravated many with his confrontational style.
Correa said votes from pro-government rural provinces and Ecuadorians abroad, many of whom left after a deep financial crisis under a center-right government, would propel Moreno, past the crucial 40 percent mark.
The new president will assume office on May 24 for a four-year term.