The leftist front-runner for Sunday's election in Bolivia, Evo Morales, has ended his campaign saying his movement is "a nightmare for the United States".
Mr Morales' campaign has been marked by anti-US slogans
Mr Morales has vowed to end free-market policies and legalise the growing of coca, which has traditional uses but is also used in the production of cocaine.
His main rival, the conservative Jorge Quiroga, ended his campaign promising to create jobs and prosperity.
Bolivia has had five presidents in four years and is a deeply divided nation.
It is currently governed by interim President Eduardo Rodriguez, who took office after Carlos Mesa was ousted amid popular protests.
Eight candidates are running in Sunday's election.
Polls suggest that Mr Morales - an Aymara Indian who is hoping to become the country's first indigenous head of state - has a slight lead over Mr Quiroga, a former president.
However, Mr Morales appears unlikely to obtain 50% of the vote, meaning that congress will have to choose a president between the two top candidates in January.
On Thursday, he told a large crowd in the city of Cochabamba that it was time for those humiliated by history to run the country, the poorest in South America.
Washington has said it expects any future Bolivian government to honour previous commitments to fight the production of illegal drugs.
Mr Quiroga, a US-educated engineer, has called for a "zero coca" policy.
A former World Bank and International Monetary Fund consultant, Mr Quiroga has said he will concentrate on getting Bolivia's foreign debt cancelled.
He told supporters in the wealthy eastern city of Santa Cruz that only his party could lead Bolivia forward.
"In this election there are two highways to choose: the highway that leads backward, that drains our resources and keeps us in underdevelopment," he said.
"Then there is the road that we want to take, the road that leads forward to progress. First we want jobs, we want to open markets, we want to build new highways."
Bolivians are also due on Sunday to elect a new congress and new prefects, or governors, in all of the country's nine departments.