Evo Morales, seeking a controversial fourth term, led Bolivia's presidential election race Sunday but faces a historic second round run-off against opposition rival Carlos Mesa, partial results showed.

Bolivia's President Evo Morales (L) casts his vote in Chapare in the department of Cochabamba Bolivia's President Evo Morales (L) casts his vote in Chapare in the department of Cochabamba Photo: AFP / AIZAR RALDES

Morales had 45 percent of the vote to Mesa's 38 percent, the Supreme Electoral Tribunal announced, with most of the votes counted.

Opposition candidate Carlos Mesa (R), a former president, is pictured after casting his vote in La Paz Opposition candidate Carlos Mesa (R), a former president, is pictured after casting his vote in La Paz Photo: AFP / JORGE BERNAL

Elected Bolivia's first indigenous president in 2005, Morales has won his previous elections in the first round, never having to contest a run-off.

People line up to vote in La Paz People line up to vote in La Paz Photo: AFP / JORGE BERNAL

The former coca farmer and leftist union leader has led the poor but resource-rich Latin American country for the past 13 years, though his popularity has waned amid allegations of corruption and authoritarianism.

He will face a stiff challenge from Mesa, a 66-year-old former president who led Bolivia from 2001-2005.

An Aymara woman casts her vote in La Paz An Aymara woman casts her vote in La Paz Photo: AFP / JORGE BERNAL

Mesa celebrated "an unquestionable triumph" in getting to the second round, amid cheers from his supporters at his La Paz headquarters.

The popularity of Bolivia's President Evo Morales has been waning The popularity of Bolivia's President Evo Morales has been waning Photo: AFP / AIZAR RALDES

Morales welcomed his first-round win, telling cheering crowds "we have won again, really, it is something historical, unforgettable".

A firefighter tries to control a blaze near Charagua, Bolivia, in August 2019 A firefighter tries to control a blaze near Charagua, Bolivia, in August 2019 Photo: AFP / AIZAR RALDES

South Korean-born evangelical pastor, Chi Hyun Chung, was the surprise package of the election, polling strongly to finish in third place with 8.7 percent.

Bolivia's 7.3 million electorate will vote in a presidential election on 20 October Bolivia's 7.3 million electorate will vote in a presidential election on 20 October Photo: AFP / Pedro UGARTE

His support is likely to be influential during campaigning for the second round on December 15.

Controversial fourth term

Morales obtained Constitutional Court permission in 2017 to run again for president even though the constitution allows only two consecutive terms.

Evo Morales welcomed his first-round win in the Bolivian presidential election, telling cheering crowds 'we have won again, really, it is something historical, unforgettable' Evo Morales welcomed his first-round win in the Bolivian presidential election, telling cheering crowds 'we have won again, really, it is something historical, unforgettable' Photo: AFP / JORGE BERNAL

A new mandate would keep him in power until 2025.

President Morales had 45 percent of the vote in the first round, the Supreme Electoral Tribunal announced, with most of the votes counted President Morales had 45 percent of the vote in the first round, the Supreme Electoral Tribunal announced, with most of the votes counted Photo: AFP / JORGE BERNAL

"Any party, no matter how good it is, if it stays in place for too long, it is corrupt, that's what we're going through," said 22-year-old student Tania Villaroel Lopez as she joined a line of voters near the presidential palace in La Paz.

Bolivia's seven million eligible voters also cast ballots to choose members of the 166-seat congress -- 36 senators and 130 deputies Bolivia's seven million eligible voters also cast ballots to choose members of the 166-seat congress -- 36 senators and 130 deputies Photo: AFP / JORGE BERNAL

Roberto Fernandez, 32, came with his wife Denise and their two-year-old daughter to vote at the same place. They said they feared the result of the elections would be manipulated.

"We hope the end result will be respected," Fernandez said.

The second round of Bolivia's presidential election will take place on December 15 The second round of Bolivia's presidential election will take place on December 15 Photo: AFP / JORGE BERNAL

Milton Quispe, a student, said he would vote for "Evo, because he has taken care of the poor. He has known how to give us dignity."

Bolivia's seven million eligible voters also cast ballots to choose members of the 166-seat congress -- 36 senators and 130 deputies.

After voting in his coca-growing district of Chapare, Morales, a member of the Aymara indigenous community, said he was optimistic about his chances and confident in Bolivia's democracy.

Opposition distrust

Mesa said he feared a rigged election after he voted in La Paz.

"I don't trust in the transparency of the process, the Supreme Electoral Tribunal has demonstrated that it's an operative arm of the government. We have a very high level of distrust," he told reporters.

Mesa lambasted what he said was Morales' powerful grip on key organs of state in a meeting with observers from the Organization of American States last week.

As leader of his Movement for Socialism Party (MAS), Morales points to a decade of economic stability and considerable industrialization as his achievements, while insisting he has brought "dignity" to Bolivia's indigenous population, the largest in Latin America.

But he stands accused of corruption, and many voters are enraged at his refusal to step aside even though the South American country's constitution bars him from running again.

"Power has replaced policies aimed at the whole population by others that only serve the interests of certain sectors," political commentator Maria Teresa Zegada told AFP.

"Opposition leaders have been persecuted, all of which has caused citizens unease and given the impression that democracy was in danger."

Bolivia's 2009 constitution, promulgated by Morales himself, limits a president to two consecutive terms of office.

In a 2016 referendum, voters defeated Morales' bid to secure public support to remove term limits, but his government rejected the result.

The constitutional court, stacked with Morales loyalists, ruled it was his right to seek re-election.

He has come under severe criticism this year as wildfires in August and September ravaged Bolivia's forests and grasslands, with activists saying his policies encouraged the use of blazes to clear farmland.