LA PAZ, August 10, 2008 (AFP) - Bolivia's recall referendum on Sunday is a bid by leftwing President Evo Morales to reassert his authority over right-leaning governors who have rebelled against his socialist policies.

The plebiscite puts on the line the mandates of Morales, Vice-President Alvaro Garcia-Linera, and eight of the country's nine governors.

Six of the governors are opposed to Morales's reforms, and five of them have formed a strong bloc in defiance.

Bolivia's total population is estimated at 10 million. Four million adults are registered to vote -- and participation is compulsory under threat of a 150-boliviano (21-dollar) fine, a large sum in Latin America's poorest nation.

The referendum asks two questions:

- Do you agree with continuing the process of change led by President Evo Morales Ayma and Vice-President Alvaro Garcia-Linera?

- Do you agree with continuing the policies, actions and management of the governor in your state?

According to congress's reading of the constitution, officials can be forced out if the proportion of ballots against them in the referendum exceeds the number of votes they received in favor in the last election, in December 2005.

That differs from the National Electoral Court's view of the rules, which says the governors can only be revoked if more than 50 percent of voters say so.

Under both interpretations, however, Morales, 48, can be made to step down if the proportion of 'no' votes is higher than the 53.74 percent of the vote that put him in the presidency.

For the governors, this list shows the amount of support each one received in 2005, and thus the threshold for 'no' votes beyond which they can be ousted under the plebiscite's terms, according to congress. The list is by region first, then the governor's name:

- Oruro, Alberto Aguilar: 40.95 percent

- Potosi, Mario Virreyra: 40.69 percent

- La Paz, Jose-Luis Paredes: 37.99 percent

- Pando, Leopoldo Fernandez: 48.03 percent

- Beni, Ernesto Suarez: 44.64 percent

- Santa Cruz, Ruben Costas: 47.87 percent

- Tarija, Mario Cossio: 45.65 percent

- Cochabamba, Manfred Reyes: 47.64 percent

The governor of Chuquisaca (Savina Cuellar) is not included in the referendum because she was only elected a month ago. She is aligned with the opposition.

If Morales loses in the referendum, presidential elections have to be held in between three and six months. Morales has said he would turn away from politics in that case, though no clear successor can be seen for his ruling Movement for Socialism party.

If a governor loses, he would be replaced pending a new election. Reyes, Morales's fiercest critic, has said he would not abide by vote against him.

Voting is to take place between 8:00 am and 4:00 pm (1200-2000 GMT). Alcohol and carrying firearms are banned until the day after the referendum.