Bolivia's Evo Morales leads vote, but appears headed for runoff

President Evo Morales led in early returns from the first round of Sunday's presidential election, but he appeared headed to a runoff in the tightest political race of his life.

The Andean country's top electoral authority said Sunday night that with 83 per cent of the vote counted, Morales was on top with 45.3 per cent, followed by 38.2 per cent for his closest rival, former President Carlos Mesa. If the results hold, they will face off in December where Morales could be vulnerable to a united opposition.

That would leave Morales about three percentage points short of the 10-point advantage needed to avoid a runoff against Mesa in which opposition parties might unite against him.

But then the release of further results halted for more than 15 hours.

"We're in a runoff," Mesa told supporters shortly after the first results were announced. He said his coalition had scored "an unquestionable triumph," and called on others parties to join him for a "definitive triumph" in the second round.

A special electoral mission from the Organization of American States said it was closely monitoring the election and urged the Supreme Electoral Tribunal to renew the release of results though the official count is not due for seven days.

Morales,a native Aymara from Bolivia's highlands, came to prominence leading social protests and rose to power as Bolivia's first Indigenous president in 2006. The 59-year-old leftist is South America's longest-serving leader.

Mesa is a 66-year-old historian who as vice-president rose to Bolivia's top office when his predecessor resigned the presidency in 2003 amid widespread protests. Mesa then stepped aside himself in 2005 amid renewed demonstrations led by Morales, who was then leader of the coca growers union.

Voting, which was mandatory, was mostly calm, though police said they arrested more than 100 people for violating the country's rigid election-day rules against drinking, large gatherings or casual driving. To avoid a runoff and win outright in Bolivia, Morales would have needed to get 50 per cent of the votes plus one or have 40 per cent and finish 10 percentage points ahead of the nearest challenger.

Morales voted early in the coca-growing region of El Chapare, where residents threw flower petals at him and he said he remained confident of his chances.

In his years in office, he allied himself with a leftist bloc of Latin American leaders and used revenues from the Andean country's natural gas and minerals to redistribute wealth among the masses and lift millions out of poverty in the region's poorest country. The economy has grown by an annual average of about 4.5 per cent, well above the regional average.

Growing dissatisfaction among Indigenous supporters

Morales, the son of Aymara Indian shepherds, has also been credited for battling racial inequalities.

Many Bolivians, such as vendor Celestino Aguirre still identify with "Evo," as he's widely known, saying people shouldn't criticize him so much. "It's not against Evo, it's against me, against the poor people, against the humble."

But Morales also has faced growing dissatisfaction even among his Indigenous supporters. Some are frustrated by corruption scandals linked to his administration though not Morales himself and many by his refusal to accept a referendum on limiting presidential terms. While Bolivians voted to maintain term limits in 2016, the country's top court, which is seen by critics as friendly to the president, ruled that limits would violate Morales' political rights as a citizen.

"I'm thinking of a real change because I think that Evo Morales has done what he had to do and should leave by the front door," said Nicolas Choque, a car washer.

Mauricio Parra, who administers a building in downtown La Paz, said he voted for Morales in 2006 as a reaction against previous centre-right governments, but this time, he voted for Mesa.

Morales "did very well those four years. ... [But]in his second term there were problems of corruption, drug trafficking, nepotism and other strange things," Parra said, saying that led him to vote against repealing term limits in the 2016 referendum. "He hasn't respected that. That is the principle reason that I'm not going to vote for Evo Morales."

Bolivians were also electing all 166 congressional seats. Polls projected that no party would have a majority in Congress, which could lead to an impasse for the upcoming administration.