President Benigno Aquino's successor risks war with disparate armed groups in the restive southern island of Mindanao if the peace pact Manila signed with the Moro Islamic Liberation Front (MILF) is cast aside, the government's peace negotiators have warned.
Such a conflict could help Islamist extremist groups get fresh recruits and turn Mindanao into a more fertile militant training ground, and also allow militants to mount more attacks across South-east Asia, they said.
After the terror attacks in Central Jakarta last month, media reports said the attackers received some support from militants operating in Mindanao.
The Philippine Congress ended its term last Friday, and the country went into the election cycle for the May 9 polls to pick a new president and elect candidates for thousands of other political posts.
But lawmakers failed to approve the proposed Bangsamoro Basic Law - the cornerstone of a deal Manila and the MILF signed in 2014 - aimed at ending a decades-long secessionist war in Mindanao, in which more than 120,000 died.
The government's chief peace negotiator, Ms Miriam Ferrer, said: "There's no incentive for the next administration to go to war. But the idea of saying you will not any more continue with the peace process is conducive to that kind of an outcome."
The MILF has said it will continue working with the government to keep the peace, but also sounded out on discontent from the ground.
MILF spokesman Mohagher Iqbal said there has been "widespread frustration" among its fighters and civilian supporters.
He added that a growing sentiment within the MILF is that "the government is resorting again to delaying tactics, and just managing the conflict in Mindanao".
Tempers are already on a hair trigger. On Wednesday, an MILF unit clashed with government forces pursuing militants from the Bangsamoro Islamic Freedom Fighters (BIFF), a breakaway MILF faction that has pledged allegiance to the extremist Islamic State in Iraq and Syria (ISIS).
Ms Teresita Deles, President Aquino's chief adviser on the peace process, said the MILF had staked its reputation on the Comprehensive Agreement on the Bangsamoro. Without the deal, she said, the MILF could break into "hundreds of smaller armed bands".
Ms Ferrer said: "Some people think that if the MILF disintegrates, they can still get a handle on the situation, which is completely the opposite (of what would happen). That's why you have this problem with Al-Qaeda and ISIS, because you don't have a handle on the situation."
BIFF is seeking "full independence" for Muslim-held areas in Mindanao, rather than just autonomy. Last week, it ambushed government troops trying to defuse a bomb strapped to a bridge project in Maguindanao province.
Another group taking advantage of the stalled peace process is the Moro National Liberation Front (MNLF). Its ageing ideologue leader Nur Misuari, 76, a former university professor, was reported to have met some 2,000 followers on Sunday to plot the group's resurgence.
The MNLF, once the largest fighting force in Mindanao, has now been decimated by defections, but it still commands enough fighters to create instability, as it did when its forces laid siege to a major port city in Mindanao in 2013.
Both BIFF and MNLF are said to have formed unwieldy ties with the Abu Sayyaf militant group that, along with other extremist elements in Indonesia and Malaysia, reportedly plans to form an ISIS province in South-east Asia.
Ms Ferrer said governments in the region would be leaning on Mr Aquino's successor to honour the government's peace deal with the MILF. "They don't want the problem in their own backyard. If it's already there, they don't want it getting worse or spreading," she said.
