MANILA - The Philippines' vicious and divisive presidential campaign ends Saturday with grand rallies and last-ditch attempts by rivals to stop Davao City Mayor Rodrigo Duterte from placing the entire country under an iron-fisted rule.

Administration candidate Mar Roxas shocked supporters on Friday when he called for "unity" with Sen. Grace Poe, with whom he was statistically tied in the last surveys before Monday's vote. Poe said she would not drop her candidacy for Roxas but was open to a meeting.

President Benigno Aquino, who had warned in campaign hustings that Duterte had the makings of a dictator, said it was crucial for rivals to unite and beat the mayor's 33-point score in opinion polls. Roxas got 20 percent versus Poe's 22 percent in the last Social Weather Stations survey.

“The whole point is to get even two of them unite... then we have more than 40 percent,” Aquino said in a television interview.

Tens of thousands of supporters of Duterte, Roxas, Poe and Vice President Jejomar Binay were scheduled to shut down different parts of the capital on Saturday, the last day of the 90-day campaign, with their respective final rallies or “Miting de Avance.”

Share prices closed 0.11 percent to 6,991.87 on Friday, for a third straight week of losses as investors kept to the sidelines, some wary over a lack of clarity in Duterte's economic platforms.

DUTERTE'S RACE TO LOSE

Duterte overtook erstwhile frontrunner Poe with promises of decisive leadership and a “bloody war” against crime. He kept a comfortable lead despite reaping criticism for cursing Pope Francis, a revered figure in the predominantly Catholic nation, and joking about the rape of an Australian missionary.

READ: Duterte under fire for cursing Pope Francis

READ: Duterte faces complaint over rape remark

The challenge for Duterte is translating loyal support both on the ground and on social media into votes, which could prove difficult because he is up against the administration party's machinery, said De La Salle University political science professor Richard Javad Heydarian.

“Duterte is clearly the outsized favorite heading into Monday's elections but there is no room for complacency,” Heydarian told ABS-CBN News.

“It's possible that much of the support for him is more campaign excitement, which may shift come election day,” he said.

Heydarian said Poe, first-term senator and daughter of the country's most popular movie stars, was in the best position to challenge Duterte, with surveys saying she was voters' top pick as “second choice” candidate.

Poe is also the “least polarizing,” Heydarian said, unlike Roxas who had toured the country burdened with the missteps of Aquino, particularly the alleged mishandling of government response to Super Typhoon Yolanda (Haiyan) in 2013.

“I doubt any will give way at this stage. It will ruin their careers,” he said.

Poe still has three years left in the Senate if she loses the election. Roxas resigned as interior secretary last year. Both the terms of Vice President Jejomar Binay and Sen. Miriam Defensor-Santiago will end on June 30.

VICIOUS CAMPAIGN

Before Friday's calls to close ranks, Duterte had come under fire for allegedly keeping P211 million in a secret account at Bank of the Philippine Islands (BPI). He admitted to the deposit but said the account contained much less.

On Thursday, anti-Duterte ads that featured children aired on primetime evening newscasts, riling the mayor's supporters. Sen. Antonio Trillanes, a vice-presidential candidate supporting Poe, paid for the ads.

Trillanes defended the ads as he took a swipe at the mayor's supporters: “Yet they laugh every time Duterte cusses and jokes about his penis and rape not realizing that children are listening too? Such hypocrisy, right? Now, that's what this ad is all about too.”

Poe, who had lived in the United States for many years, nearly had her bid derailed after her citizenship was questioned before Supreme Court, which ultimately ruled in her favor.

She has also parried criticism over her association with political figures previously associated with corruption like Manila Mayor Joseph Estrada and San Miguel Corp. Chairman Eduardo Cojuangco Jr.

Even before Duterte and Poe declared their candidacies, Binay had faced numerous allegations of corruption, including an alleged overpriced parking building construction in Makati City when he was still mayor. He could face criminal charges after he steps down.

Aside from Yolanda, Roxas, a former transportation secretary, has been blamed for daily traffic jams and train breakdowns that have made commuting a daily misery in the capital city of 12 million people. Polls showed Roxas had poor support in Metro Manila.

A possible Duterte has not only unnerved the markets, it also appeared to have caused restiveness among the military due to the mayor's perceived closeness with the Left.

Coup rumors swirled after a video of a masked man claiming to be a soldier surfaced on internet. The man warned of a looming takeover by leftist rebels.

“Whether Duterte wins or loses, the country is set for huge uncertainty,” Heydarian, the political analyst said.