Sucre, Bolivia, Oct 21 (UNI) Bolivian President Evo Morales is set to face a run-off vote for the first time after failing to secure a fourth consecutive term at Sunday's general election, according to partial results, says a BBC News report on Monday.
Mr Morales had 45pc of the vote to 38pc of former President Carlos Mesa with 83pc of the votes counted.
But the transmission of results was interrupted.
Mr Morales is a divisive figure, praised for his social policies but criticised for defying term limits.
If Mr Morales, Bolivia's first indigenous leader who has been in power since 2006, wins another term, he will be in power until 2025. A run-off vote is due to take place on 15 December.
Mr Morales, who has won all his previous terms in the first round, needs 40pc with a 10-percentage-point lead over his nearest rival or more than 50% of the votes to win outright.
Observers from the Organisation of American States have asked the electoral commission to explain why the transmission of results stopped.
On Twitter, Mr Mesa called the incident "extremely serious", saying: "We're not going to allow the manipulation of a result that obviously puts us in a second round."
But addressing cheering supporters in the capital, La Paz, Mr Morales said he was confident that when votes from rural areas were counted there would be no need for a run-off.
"The rural areas are going to keep guaranteeing this process of change," said Mr Morales, already Latin America's longest serving leader.
"That's why, sisters and brothers, we're going to wait until the last vote is counted to pursue and continue our process of change."
These were the most uncertain elections for Mr Morales, with many people angry with his insistence on running again, BBC South America correspondent Katy Watson in La Paz reports.
In a referendum in 2016, Bolivians rejected his suggestion to ditch the presidential term limits.
But his Movement for Socialism (Mas) party took the matter to the constitutional court, which ruled in the president's favour, allowing him to stand for a fourth term.
Bolivians have also criticised his environmental policies, after forest fires that destroyed four million hectares of land in eastern Bolivia.
Many question whether a decree passed by the president, which quadrupled the amount of land farmers are allowed to clear for agricultural production, contributed to the blazes.
President Morales, 59, has been widely praised for growing the Bolivian economy and, at the same time, cutting extreme poverty.
Many indigenous Bolivians continue to back him, saying Mr Mesa - who is running for the Civic Community (Comunidad Ciudadana) political alliance - embodies the white Bolivian elite and question his commitment to the poor.
In the election campaign, Mr Mesa argued that with oil and gas revenue declining, Bolivia needed to be "more sensible and rational" in the way it spends its money, especially as the country has a fiscal deficit of 7.8% of GDP.
But his message of curtailing spending has not proven popular with poor voters who have seen steady improvements to their quality of life under President Morales.
UNi SNU 1020