Senator Manny Pacquiao accepted the nomination of the PDP-Laban party at its national convention on Sunday.
The 42-year-old lawmaker said the Filipino people have been waiting for a change of government.
“I am a fighter, and I will always be a fighter inside and outside the ring,” Pacquiao said in his speech.
Pacquiao has taken a strong line against corruption and blamed President Duterte for the worsening situation in the country.
“We need government to serve our people with integrity, compassion and transparency,” Pacquiao said.
Pacquiao and Senator Aquilino “Koko” Pimento III lead the PDP-Laban faction while the other faction is headed by President Rodrigo Duterte.
Duterte party mates say they will petition the Commission on Elections to declare Pacquiao an illegitimate party officer.
Last month, the Duterte faction nominated him as its vice presidential candidate and Duterte’s former aide, Senator Bong Go, as its presidential bet.
While Duterte has accepted his nomination, Senator Go has declined. Duterte can no longer run for reelection as president.
Once an ally of Duterte, Pacquiao has accused the current administration of making corruption worse in the Philippines. Duterte won his presidency on an anti-corruption campaign in 2016.
Pacquiao in July had said more than 10 billion pesos intended as pandemic aid for low-income families were unaccounted for. He also accused President Duterte of not defending the West Philippine Sea against China’s incursion.
Duterte’s ire resulted in Pacquiao being ousted as president of the ruling party.
Pacquiao is likely to face the presidential daughter, Mayor Sara Duterte-Carpio, who is expected to run for the top post in next year’s Presidential Elections.
Critics question Pacquiao’s qualifications and competence for the presidency. The famous boxes said his experience of personal hardships would better equip him to understand people’s suffering and would enable him to fight poverty and corruption.
“In my whole life, I have not backed down on any fight,” Pacquiao said.
He warned politicians whom he holds responsible for corruption “will soon end in jail together.”
Born to an impoverished family, Pacquiao started his professional boxing career at the age of 16. He gained popularity with his constant wins and knockouts against renowned boxers, becoming one of the best boxers of all time.