The people of Bolivia go to the polls on Sunday in a referendum to decide whether President Evo Morales may stand for a third term.
The country’s first president of indigenous origin faces a tough challenge after 10 years in power.
He called a referendum to ratify constitutional amendments approved by parliament last year.
Mr Morales says he needs a third term for social reforms but the opposition says the change is undemocratic.
“On Sunday we will win big,” Mor Morales said during the campaign. “The people will decide and there will be a lot to celebrate.”
Mr Morales, an indigenous Aymara and former coca leaf producer, took office in January 2006.
His second term ends in 2020 but he will be able to run for another term in 2019 and serve until 2025 if the referendum is approved.
Mr Morales has already been elected three times but argues that the first term does not count because a new constitution was approved in 2009, re-founding the country as Plurinational State of Bolivia.
Despite a drop in the international price of oil and natural gas, the Bolivian economy has performed well in the past 10 years, growing on average 5% a year.
The government’s socialist policies have also been successful in reducing extreme poverty.
But recent allegations that Mr Morales used his influence to favour a Chinese construction firm in Bolivia have damaged his approval ratings.
A former girlfriend of Mr Morales, Gabriela Zapata, holds an important position in the company, CAMC, which has secured more than $500m (£350m) in contracts with the Bolivian government
Mr Morales rejected the allegations and said he had nothing to hide. He ordered an investigation into how the contracts were awarded.