The son of late Philippine dictator Ferdinand Marcos wrapped up his presidential election campaign Saturday with a raucous rally of hundreds of thousands of supporters, as polls show him heading towards a landslide win.

Victory in Monday's election would cap a decades-long effort to rehabilitate the Marcos legacy after the patriarch was deposed and the disgraced clan chased into US exile.

But the prospect of Ferdinand Marcos Jr moving back into the presidential palace has alarmed rights activists, church leaders and political analysts who fear he could rule "without constraint".

The Marcoses' remarkable return from pariahs to the peak of political power has been fuelled by public anger over corruption and poverty that persisted under governments that followed the dictatorship.

Hundreds of thousands of red-clad Marcos supporters on Saturday amassed on a dusty wasteland overlooked by a gleaming luxury casino resort -- a stark reminder of the country's vast income gap.

Wielding national flags, they gathered before a stage featuring an enormous screen of the smiling candidate as Filipino reggae, hip-hop and pop played at deafening levels.

The prospect of Ferdinand Marcos Jr moving back into the presidential palace has alarmed rights activists, church leaders and political analysts
The prospect of Ferdinand Marcos Jr moving back into the presidential palace has alarmed rights activists, church leaders and political analysts AFP / Ted ALJIBE

"We will win as long as you stay awake on Monday so there won't be another tragedy," Marcos told the crowd, referring to his claims that he was cheated of victory in the 2016 vice presidential race.

Mary Ann Oladive, a 37-year-old call centre worker, said she hoped Marcos Jr would bring unity to the country.

"We hope for greater opportunity and jobs. We trust him, we hope that after the election they will give us a better future in the Philippines," she said.

Ten candidates are vying to succeed President Rodrigo Duterte in the landmark elections seen by many as a make-or-break moment for Philippine democracy.

Leni Robredo's recent poll bump has raised hopes among progressive supporters that their volunteer-driven campaign could yet deliver an upset but analysts say there is little chance of that
Leni Robredo's recent poll bump has raised hopes among progressive supporters that their volunteer-driven campaign could yet deliver an upset but analysts say there is little chance of that AFP / CHAIDEER MAHYUDDIN

Polls indicate Marcos Jr will win more than half the votes, which would make him the first presidential candidate to secure an absolute majority since his father was ousted in 1986.

Analysts warn such an outcome would lead to weaker democratic checks and balances, more corruption and a fresh attempt to overhaul the 1987 constitution -- which could include scrapping the one-term limit for presidents.

Previous administrations, including Duterte's, have tried to amend the constitution, but they lacked sufficient support in Congress to push through changes.

The latest poll by Pulse Asia Research showed Marcos Jr on 56 percent -- 33 percentage points ahead of his nearest rival Leni Robredo, who narrowly beat him in the 2016 vice-presidential race.

Such a winning margin would give Marcos Jr the power to "govern the way Duterte wanted to", one long-time observer of Philippine politics told AFP.

"That is without constraint," he said.

Robredo's recent poll bump has raised hopes among progressive supporters that their volunteer-driven campaign could yet deliver an upset.

Polls indicate Marcos Jr will win more than half the votes, which would make him the first presidential candidate to secure an absolute majority since his father was ousted in 1986
Polls indicate Marcos Jr will win more than half the votes, which would make him the first presidential candidate to secure an absolute majority since his father was ousted in 1986 AFP / JAM STA ROSA

There was a carnival atmosphere in the capital's financial district on Saturday as hundreds of thousands of Robredo fans wearing her pink campaign colour and waving flags and balloons packed out avenues, dancing to live Pinoy pop blaring over loudspeakers.

In a rousing speech, Robredo told her supporters there was "always hope" and declared "victory awaits us".

First-time voter Charmaigne Ang, 18, said the election was "very important".

"Our next six years of life will depend on it," Ang, 18, told AFP. "Surveys are not a basis of who will win."

But pollster Ana Maria Tabunda of Pulse Asia Research gave Robredo little hope.

"Our error margin is only plus or minus two percentage points -- given the large gap, it's not going to be affecting the results," Tabunda told AFP.

Allegations of dirty tricks marred the last week of a bitter presidential campaign, as Marcos Jr warned of vote-rigging while Robredo accused him of being a "liar".

Marcos Jr has run a tightly-controlled campaign, skipping televised debates with rivals and largely shunning media interviews to avoid own goals before election day.

A massive and well-funded social media misinformation campaign targeting a mostly young electorate with no memory of his father's violent and corrupt rule has also sought to rewrite the family's history.

Marcos Jr's popularity has been further enhanced by a formidable alliance with vice-presidential frontrunner and first daughter Sara Duterte, and the backing of several rival political dynasties.

Days ahead of the election, rights defenders and many Catholic priests made a final push to stop Marcos Jr returning to the Malacanang Palace, where he grew up.

"It will be another six years of hell," warned political satirist and activist Mae Paner, 58, who was part of a popular uprising that ended the elder Marcos's regime and has been campaigning for Robredo.

Hundreds of priests endorsed Robredo and her running mate Francis Pangilinan, telling their flocks the election was a "battle for the soul" of the nation.

But after enduring six years of attacks from the elder Duterte, Robredo has seen her popularity hammered by a relentless and vicious online smear campaign.

Political analyst Richard Heydarian said Robredo's late decision to enter the race had cost valuable time, while "unnecessary infighting" among rival candidates had benefited Marcos Jr.

"They are handing this on a silver platter to the princeling of Philippine politics, Bongbong Marcos," he said, using Marcos Jr's nickname.