LA PAZ, Dec. 6 (Xinhua) -- Bolivia is to hold general elections on Sunday to choose a new president, a vice president and deputies to both houses of parliament. Following is a brief introduction to three leading presidential candidates.

    -- Evo Morales, 50, incumbent president and candidate of the Movement Toward Socialism (MAS), is leading the opinion polls with more than 50 percent of support. If the numbers are repeated at the ballot box, Morales will be re-elected to a five-year term.

    Morales, Bolivia's first president of indigenous descent, won the elections of December 2005 with 53.7 percent of the vote. He took office in January 2006.

    Born in an indigenous family in Orinoca in the Oruro department, he worked as a herdsman and a farmer in his early years and joined the military service at 16 years.

    Morales was executive secretary of the Tropic Federation Coca Growers' Union in 1988 and executive secretary and president of Six Federations of the Cochabamba Tropics Coca Growers' Union in 1996. He was deputy of Chapare and Carrasco provinces of the Cochabamba department in 1997-2002.

    In October 2003, Morales was instrumental in leading mass protests that led to the resignation of former president Sanchez de Lozada in the so-called Bolivian "Gas War."

    In January 2009, a referendum in Bolivia gives more power to the country's indigenous majority and allows Morales to seek re-election.

    -- Manfred Reyes Villa, conservative candidate and a former governor, is Morales' closest rival with about 20 percent of support.

    Reyes Villa, born in 1955 in La Paz, went to live and work in the United States in 1986. Reyes Villa returned to Bolivia at the beginning of the 1990s and began his political career in the right-wing party of Nationalist Democratic Actions (AND). He was in charge of the Cochabamba department from 1993 to 2000.

    -- Samuel Doria Medina Auza, 51, candidate of the National Unity, is a politician, economist and businessman who had a Master's degree at the London School of Economics in England.

    He has been director and shareholder of different cement and food companies, and is an authorized franchise holder of the U.S. fast food chain Burger King in Bolivia. Doria is also a member of the Economic Commission of the Private Businessmen Commission of Bolivia.