The head of Bolivia's top electoral body praised "a successful day for democracy" and called for calm as citizens waited for the results of Sunday's general election.
Results are expected to be slower than usual as the Electoral Tribunal suspended the customary rapid count, arguing that it couldn't guarantee its accuracy.
But Salvador Romero, president of the Supreme Electoral Court, insisted that the manual vote count, although slow, was being done "cleanly, transparently, with the participation of the political parties."
Likewise, Bolivia's interim president Jeanine Anez, who was not a candidate, called for "patience" and urged citizens to avoid "any type of violence."
But exiled former president Evo Morales took to Twitter accusing electoral authorities of "refusing to publish results" and suggested they were trying to "hide" something.
Luis Arce, the candidate from Morales's Movement for Socialism (MAS) party, has led polls since he was nominated in January.
Campaigning was tense and polarized, with MAS warning of a pending "fraud."
"We've had a calm day throughout the whole country up until now," Deputy Security Minister Wilson Santamaria said in a statement.
He mentioned two minor instances in La Paz where people tried to interfere with voting papers but said they had been prevented and apprehended.
Polling stations were open from 8:00 am to 5:00 pm (1200-2100 GMT), but some had to stay open longer as queues of people were still waiting to vote.
- 'Not ideal' -
Arce is expected to win Sunday's first round, but the question is whether the 57-year-old can achieve the required 40 percent of votes with a 10-point lead to avoid a run-off.
If not, polls suggest centrist former president Carlos Mesa, 67, would triumph in a run-off with support from the other four candidates.
"It's not ideal but we understand that (the electoral body) has chosen the path to guaranteeing absolute security of the vote and above all the official count," Mesa said about the slow count.
The election, which was twice postponed due to the coronavirus pandemic, was the first in 20 years not to feature Morales, the country's first ever indigenous leader.
It came a year after Morales won an unconstitutional fourth term in a controversial election that sparked weeks of protests.
The rapid count in 2019 suggested there would be no outright winner, but after it was inexplicably frozen for 24 hours, Morales had jumped into a winning lead over Mesa once the live count resumed.
A later audit by the Organization of American States found clear evidence of fraud.
Morales, who resigned and fled into exile after almost 14 years in power, is barred from taking part but tried to ratchet up tensions during campaigning from his base in Argentina.
But before the count began, Morales had urged calm and said "the election result must be respected by everyone."
He also promised to return to Bolivia -- where he is being investigated for "rape and trafficking" over allegations he had relationships with underage girls, and even fathered a child with one -- "the next day" should his former finance minister Arce win.
- 'I fear the worst' -
Voting, which is mandatory up to the age of 60, was slow in part due to social distancing rules imposed over the coronavirus pandemic.
"I hope the next president will be a candidate who helps the countryside, the poor people," Silverio Chirinos, a 69-year-old farmer in Huarina on the shores of Lake Titicaca, told AFP.
Some, however, expected trouble.
"Obviously there will be social upheaval... we just hope it won't last long," Clara Quitalba, 49, from the MAS bastion of EL Alto on the outskirts of La Paz, told AFP.
"I don't know what will happen, but I fear the worst," said Virginia Luna, 41, in La Paz.
Last year's protests left 36 dead and 800 injured.
Observer missions from the European Union, OAS and the Carter Center are present, while United Nations General Secretary Antonio Guterres has called for the result to be respected.
The vote will bring to an end the year-long interim presidency of conservative Anez, who withdrew from the race a month ago as criticism rose of her handling of the coronavirus pandemic that has left more than 8,400 people dead and infected 130,000.
Landlocked Bolivia, one of the poorest countries in the region despite its rich natural resources, is also experiencing its worst economic crisis in 40 years, with GDP expected to contract by 6.2 percent in 2020.
As well as choosing a new president, the 7.3 million eligible voters will elect a new Congress, where both chambers are currently controlled by MAS.
Although likely to remain the largest party, MAS is expected to lose its overall majority in the chambers.