A victory in the vote would allow Morales to expand leftist reforms that have made him popular with the country's poor, but have angered powerful business groups.
The president is credited with a 60 per cent approval rating, much of which comes from Bolivia's indigenous majority.
But he has recently reached out to the country's middle class in an effort to expand his popularity.
"I'm surprised so many sectors are supporting [me]," the Reuters news agency quoted Morales as telling reporters last Tuesday.
"What are the businessmen and the upper-middle classes saying? They are saying: it will be an Indian, but he has respected us.
"You have to support Evo Morales. Those are good messages and that makes me think that [we will win] more than 70 per cent [of the vote]."
Since he took office in 2006, Morales has instituted quotas to give Indians posts in the military and created a special school for aspiring diplomats with native backgrounds. He has also started three indigenous universities.
A close ally of Hugo Chavez, Venezuela's president, Morales also nationalised Bolivia's oil and gas sector in a move that helped lift the country's economy out of the red and left $8bn in reserves.
But he has also angered other Bolivians who have seen their landholdings decreased as part of the president's reforms.
His potential re-election to a second term was made possible after Morales won a referendum that lifted the one-term limit for president.
The move mirrored similar moves by other Latin American leaders including Chavez and Rafael Correa, Ecuador's president.