Bolivian President Evo Morales answers questions from the press at Quemado palace in La Paz on February 22, 2016
La Paz (AFP) - Bolivia's President Evo Morales stood firm Tuesday in the face of likely defeat in his bid to seek a fourth term, refusing to concede until final referendum results trickle in.
Morales, 56, has been in power for a decade, thanks in large part to support from indigenous groups and grassroots organizations in one of the Americas' poorest countries.
He promised to respect the official results of Sunday's vote on a constitutional reform that would let him run for re-election to extend his time in office to 19 years. His current term ends in 2020.
Provisional official results released Tuesday by the electoral board with nearly 83 percent of votes counted indicated about 52 percent for "No," and 47 percent for "Yes."
But Morales insisted on waiting for full results to come in from rural areas where he has strong support, and from abroad.
"If we overturn this early count, it will be with the votes of the social movements, especially the indigenous votes in the countryside," he said during a public appearance.
But he later acknowledged: "If we win, it will be by a few votes. If we lose, it will be by a few votes."
- Opposition claim victory -
The partial official results were in line with exit polls published by private media, which indicated Morales lost the vote.
Political scientist Jorge Lazarte said the results showed that "part of the country... has said enough is enough" and this will force Morales to now seek consensus with the opposition.
Opposition groups feared the government was preparing to manipulate the result.
Groups chanting "Fraud! Fraud! Fraud!" staged a sit-in outside the office in La Paz where votes were being counted late Monday.
The mood was calm overall across the country of 10 million, however.
Organization of American States observers issued a statement urging all sides to accept the results when the electoral board publishes them.
Other opposition figures celebrated their projected victory.
Samuel Doria Medina -- defeated twice by Morales in presidential elections -- said, "We have recovered democracy and the right to choose."
Morales had earlier said he was prepared to give up on a fourth term if voters rejected the bid.
"With my record, I can leave happily and go home content. I would love to be a sports trainer," he was quoted as saying in an interview with Spanish newspaper El Pais.
- Economic growth, corruption -
In January, Morales became the longest serving president since Bolivia's independence from Spain in 1825 -- rare in a country that has seen numerous military coups.
He is one of a generation of Latin American leftist leaders who champion "21st-century socialism."
Since first taking office, he has been strongly re-elected twice and has overseen robust economic growth.
Bolivia's mineral- and gas-rich economy has more than tripled in size during his decade in office.
But opponents accuse him of presiding over corruption and wasteful spending.
His popularity has suffered from allegations that he used his influence in favor of contracts for CAMC, a Chinese engineering company that employs his ex-girlfriend.
A defeat could disrupt the remainder of Morales's term and his Movement to Socialism (MAS) party, a grouping of unions and social movements, analysts say.
"These results will probably cause an internal struggle to replace him," analyst Andres Torres told AFP.
"It could weaken the party and cause an implosion with serious problems for the MAS in the four years it has left in government."
But analysts at the Eurasia Group consultancy said Bolivia's relatively strong economy made it "unlikely" that the country would suffer instability in the short term.