Bolivian socialist leader Evo Morales has won enough votes in the country's presidential election to be installed as leader, electoral officials say.
Evo Morales has adopted a measured tone since the election
The country's electoral court confirmed that with almost two-thirds of the votes counted, Mr Morales' share was enough for him to win.
Mr Morales, an indigenous Aymara coca farmer, has called for an alliance with the US against drug trafficking.
In a BBC interview, though, Mr Morales defended traditional uses of coca.
Mr Morales' win has raised eyebrows in the US, after he expressed his admiration for the Cuban leader Fidel Castro and Venezuelan President Hugo Chavez.
He has also pledged to fight to remove the coca plant from the United Nations list of poisonous plants, and stressed his keenness to increase state control over Bolivia's lucrative natural gas industry.
Officials within Bolivia's interim administration are reportedly preparing to hand over power to Mr Morales.
Electoral officials suggested that Mr Morales' margin of victory over his rival, Jorge Quiroga, would be large enough for him to be declared winner by Congress even if his eventual total dipped below the 50% threshold.
At a news conference in La Paz, Mr Morales insisted that he would not deliberately seek confrontation on key policies.
"It's not about conquering, it's about convincing, persuading about our concrete proposals with transparency and honesty," he said.
Mr Morales' policy on coca production and drug trafficking is likely to be keenly watched by the US.
Previously, Mr Morales claimed that Washington had used drug-trafficking as a pretext for installing military bases in the region.
The US said future relations with Bolivia would depend on Mr Morales's behaviour in office.
"The issue for us is: Will the new Bolivian government govern democratically? Are they open to co-operation that, in economic terms, will undoubtedly help the Bolivian people?" US Secretary of State Condoleezza Rice told reporters.
Bolivia's indigenous people, who make up more than half the population, generally support the man who pledges to legalise the production of the coca leaf, but who repeatedly stresses that: "Coca is not cocaine".
Mr Morales also vowed to join what he called the anti-imperialist struggle of Mr Castro, the Cuban leader.
Mr Morales has promised to make foreign oil and gas investors pay what he says is a fairer share to Bolivians, but he made clear that his political party, the Movement towards Socialism (Mas), would never "extort" foreign investors.
Washington has said it expects any future Bolivian government to honour previous commitments to fight the production of illegal drugs.
Bolivia, South America's poorest state, has had five presidents in four years.
Bolivians also voted for a new parliament, or Congress, and regional governors on Sunday.