Philippines' President Ferdinand Marcos Jr delivers his speech during the 88th anniversary of the Armed Forces of the Philippines at Camp Aguinaldo military headquarters in Quezon city, Philippines on Dec 21, 2023. (PHOTO / AP)

MANILA - Former Philippine leader Rodrigo Duterte's son urged President Ferdinand Marcos Jr to resign on Sunday, calling him lazy and uncompassionate in a deepening rift between the two politically powerful families.

Marcos teamed up with Duterte's daughter Sara to make her vice-president in their 2022 election win. But cracks in the families' alliance have emerged as the incumbent has veered away from his predecessor's anti-drugs and foreign policies.

Marcos' alliance with the Dutertes was crucial to his presidential victory, so a souring of their relations could have implications in his bid to solidify his support base ahead of the mid-term Senate and congressional election next year

Sebastian Duterte, who is mayor of Philippines' third most populous city Davao, said there had been a resurgence in crime after his father's hardline campaign had been relaxed.

At a leadership forum, he also accused Marcos of endangering innocent Filipinos by allowing the Americans in, a reference to expanded US access to military bases.

ALSO READ: The Philippines should not let US use it as a lightning conductor in its storm making

"You are lazy and you lack compassion. That's why we are unfhappy," he said.

There was no immediate comment from Marcos' office.

Mid-term elections loom

He spoke just before Marcos took the stage at a government-led rally in the capital to drum up support for his "Bagong Pilipinas (New Philippines)" campaign, where he has promised to improve state services and budget transparency.

Marcos' alliance with the Dutertes was crucial to his presidential victory, so a souring of their relations could have implications in his bid to solidify his support base ahead of the mid-term Senate and congressional election next year.

READ MORE: Marcos: Philippines won't assist in ICC's drugs war probe

Sara Duterte, who is also education secretary, attended the president's rally before flying to Davao to join her father and siblings at a prayer rally against moves to amend the Philippine constitution, which Marcos backs.

Some opponents of constitutional change, including the Dutertes, say it is driven by an agenda to change the political system and remove term limits, including that of the president, who can currently serve just one six-year term.

"He is putting politics first, their self-preservation ... rather than focusing on the job," Sebastian Duterte said.

"Mr. President, if you have no love and aspirations for the nation, resign."

READ MORE: Philippines' Marcos draws ire for helicopter use for Coldplay concert

Like her brother, Sara Duterte has openly defied some of Marcos' policies, including the peace talks with communist rebels which she said was an "agreement with the devil".

Asked for comment on her brother's remarks, Sara Duterte said on Monday: "I can only surmise he is coming from a place of brotherly love, coupled by the common sentiment that I do not deserve the despicable treatment that I am receiving from some sectors within the circle of the president."

Sara Duterte did not elaborate, but said she "will stay true" to her work at the education ministry.