Bolivian authorities are counting ballots from Sunday's national elections for a new president, vice president and Congress.
Two independent voter exit polls put leftist presidential candidate Evo Morales 10 percentage points ahead of conservative former president Jorge Quiroga.
If Mr. Morales wins, he would become Bolivia's first indigenous president. The coca farmer has said he would reverse efforts to eradicate coca fields and increase government control of the country's natural gas resources.
If neither Mr. Morales or Mr. Quiroga wins 50 percent or more of the vote, Bolivia's newly elected Congress will choose between the two leading contenders.
The vote was monitored by international observers and 50,000 police and security personnel