MANILA, Philippines — Minutes after former Philippine leader Rodrigo Duterte was bundled onto a plane bound for The Hague to face a charge of crimes against humanity, President Ferdinand Marcos said of the arrest: "Politics doesn't enter into it."

Complying with the International Criminal Court warrant tied to his predecessor's deadly drug war was simply a matter of the Philippines meeting its international obligations, he told reporters.

But Tuesday's shocking arrest, which comes barely a month after the impeachment of Duterte's daughter Sara, the country's vice president, has left the family's national political fortunes in deep peril, analysts told AFP.

"Let me put it this way. Their situation wasn't promising in the first place, even before all of these things happened," said Michael Henry Yusingco, senior fellow at the Ateneo Policy Center, pointing to polling for May's mid-term elections.

Only three candidates from Duterte's PDP Laban party are on track to grab one of the 12 nationally elected Senate seats, while Marcos's ruling New Philippines Alliance has eight candidates firmly among the leaders.

Those elected will hold the deciding votes in the trial of the vice president, impeached last month on charges of graft, corruption and an alleged plot to assassinate her former running mate Marcos.

Given Marcos's "full control of the critical levers of government... it's certainly reasonable to speculate that this could be the end" of the Duterte dynasty, said Yusingco, while cautioning it was too early "to make a definitive judgment".

Cracks in the Marcos-Duterte alliance were already showing within weeks of the landslide 2022 election victory, with the vice president angered when she was denied the coveted defence portfolio.

But the simmering feud erupted in the months leading to her impeachment, which was overseen by House Speaker Martin Romualdez, a Marcos cousin.

Public sniping between the two dynasties saw the elder Duterte label Marcos, the one man who could have shielded him from the ICC, a drug addict.

The president, in turn, has spent much of his recent time on the campaign trail railing against Duterte's bloody drug crackdown.

"At the end of the day, (the arrest) would not have happened had there not been a rift between the two of them," said Jean Franco, assistant chair of the University of the Philippines' political science department.

'Caught off guard'

The former president, due in court on Friday, was arrested three days earlier at Manila's international airport after returning home from a trip from Hong Kong in the face of rumours an ICC warrant had been issued.

The decision to return may have been because he hoped "to portray himself as a victim", political analyst Richard Heydarian told AFP, a gambit that immediately backfired.

"The government outsmarted him by making sure that they had a mechanism in place to... whisk him away directly to The Hague," Heydarian said.

"I think that really caught them off guard because I think the Dutertes were hoping to... employ legal delaying tactics," he said, like taking it to the courts to buy supporters time to mount large-scale rallies.

But the speed of Duterte's transfer to The Hague -- arrested and flown out on the same day -- made any such plans moot.

While Franco agreed some voters may have bought into a victim narrative, Yusingco was less convinced.

"Voters will not be swayed in (the Dutertes') favour just because he was arrested," he said.

Charisma deficit

No matter the outcome of May's election, the vacuum left by Duterte's exit may be impossible to replace from within the family ranks.

"My sense is that the charisma of the Dutertes is really largely because of the elder Duterte," said Franco.

"I don't think (Sara) or the sons (one a congressman, another the mayor of family stronghold Davao) actually inherited his brand, the charisma he has for their base."

And expecting the increasingly frail 79-year-old patriarch to lead the family's fight-back from a cell in The Hague was unrealistic.

"I imagine it would be extremely, extremely difficult given his age... (more than) the fact that he's detained," Yusingco said.

However, he added that "you can never underestimate a politician like former president Duterte".

"He may still have allies out there that can still make noise and still mobilise," Yusingco said.

Franco, meanwhile, said she believed it was his daughter's impeachment that might mark "the beginning of the end for the Duterte brand".

"Of course," she added, "in Philippine politics, you can always rebrand."