By Daniela Desantis and Mariel Cristaldo
ASUNCION (Reuters) - The candidate from Paraguay's ruling Colorado Party won Sunday's presidential election, according to official results with 96 percent of ballots counted, pointing to another five years of pro-business policies in the major soy producer.
The country's elections authority said Mario Abdo, a 46-year-old former senator who campaigned on an anti-corruption platform, had an "irreversible" advantage over his main rival, Efrain Alegre, a lawyer from the center-left GANAR coalition.
"My administration will be committed to gaining the confidence of those who did not accompany us," Abdo said in his acceptance speech.
Abdo had 46.49 percent of the vote to Alegre's 42.72 percent, the head of Paraguay's elections tribunal, Jaime Bestard, said on television. "The president-elect of Paraguay is Mario Abdo," Bestard said.
Abdo supports current low-tax policies aimed at stimulating foreign investment and agricultural production in the world's No. 4 soybean exporter and a major supplier of beef.
The margin of victory was much tighter than indicated by pre-election opinion surveys, which gave Abdo a voter intention advantage of 18 to 20 points. Alegre said he would not concede the race until all ballots were counted and confirmed.
Abdo set the stage for governing with a minority in Congress by calling for dialogue with opposition parties. He has promised to fight pressure to raise taxes despite calls from the opposition for a levy on soybean exports.
Outgoing President Horacio Cartes, who tried to change the constitution to allow him to seek a second term, won a Senate seat in Sunday's vote.
Abdo is the son of the late private secretary of dictator Alfredo Stroessner, who ruled Paraguay with an iron hand for 35 years. Abdo was 16 when Stroessner's rule ended in 1989.
Earlier on Sunday, Abdo visited the tomb of his father, as he did on the day of the primary election in December when he won the nomination of the Colorado Party.
Abdo's conservative policies and family history were a concern to some voters who had doubts about his commitment to clean up government.
"This is a country of corruption and until we end that, we will not move forward. Mario Abdo is a son of the dictatorship and I do not think he will govern well," Edgar Gonzalez, 45, said on his way out of his voting station in a high school in the upper-middle-class neighborhood of Trinidad in Asuncion.
Abdo's father was also named Mario, giving the nickname "Marito" or "Little Mario" to his son, as he is popularly known.
About 4.2 million Paraguayans were eligible to vote in the election, in which all seats in Congress were up for election. The new president will take office on Aug. 15. Official congressional election results were to be announced over the coming days.
SOY TAX DEBATE
Grains-dependent Paraguay produced more than 10 million tonnes of soy last year and is trying to attract investment needed to reach its goal of 20 million tonnes by 2028.
Abdo's party went into the election with 20 seats in Paraguay's 45-member Senate, which last year debated a bill to slap a 10 percent tax on soybean exports.
"The push for an export tax will intensify after the election, which is likely to see the empowering of the Frente Guasu, a major proponent of the initiative, and a party which is expected to substantially increase its presence in Congress," said Thomaz Favaro, an analyst for consultancy Control Risks.
Abdo may have to support the export tax to safeguard other parts of his investment-friendly agenda.
"Uncertainty over the level of taxation for the agriculture industry will thus likely persist in the short-to-medium term," Favaro said.
(Reporting by Daniela Desantis and Mariel Cristaldo; Writing and additional reporting by Hugh Bronstein; Editing by James Dalgleish, Peter Cooney and Cynthia Osterman)