Benigno Aquino is poised to continue his family's legacy in the Philippines by winning the country's presidential election.
With most districts counted, Mr Aquino had about 40% to 25% for his closest rival Joseph Estrada, the BBC reports.
Mr Aquino's father was assassinated in 1983 on his return from the United States to oppose the dictatorship of Ferdinand Marcos, and his mother Corazon subsequently became president.
Incumbent Gloria Arroyo's second term expires in June.
As in previous elections, the poll has been overshadowed by violence. At least 10 people were killed in gun and grenade attacks in and around polling stations, mostly in the volatile south of the country.
Some voters - including Mr Aquino - queued for several hours at polling stations after newly-introduced voting machines malfunctioned.
However, officials insisted that all votes would be counted and kept polling open to accommodate the delays.
More than 17,000 positions are at stake - from president down to municipal council seats.