Former Philippines president Rodrigo Duterte registered his candidacy on Monday to run for mayor of the southern city of Davao in midterm polls due next year.
Davao is the family stronghold of Duterte, who as president launched a deadly drug war in 2016 that is the subject of local and international investigations.
His decision to run for mayor follows a bitter, public falling out with the family of Philippines President Ferdinand Marcos ahead of presidential elections in 2028.
"I want to serve you," 79-year-old Duterte, the father of Vice President Sara Duterte, told reporters after submitting his candidacy documents in Davao City.
His running mate will be his son and incumbent Davao mayor, Sebastian Duterte, and he said he planned to make Davao "better than yesterday".
The former president's decision to run is seen as a move to galvanise support for his daughter Sara, who is widely expected to run for president in 2028.
The 2025 midterm vote is crucial for both the Duterte and the Marcos families as they seek to shore up their support bases before that race.
"We have to remember that the basic rule in politics is protect one's bailiwick at all cost," Duterte's former spokesman Harry Roque said in a social media post.
The International Criminal Court is investigating allegations of human rights abuses committed during Duterte's drug war, which has continued under Marcos.
The House of Representatives is also conducting committee hearings on the drug war killings.
More than 6,000 people were killed in anti-drug operations under Duterte, according to official data released by the Philippines. ICC prosecutors estimate the death toll at between 12,000 and 30,000.
Sara Duterte is facing impeachment threats in the House of Representatives, which is led by Speaker Martin Romualdez, Marcos's cousin, who is also expected to run in 2028.