MANILA, Philippines -- A brash mayor known for sex jokes and a pledge to end crime within six months -- by killing suspected criminals if necessary -- strongly led an unofficial vote count in Monday's Philippine presidential election, while the son of late dictator Ferdinand Marcos led in the vice-presidential race.

Mayor Rodrigo Duterte reached out to his opponents following a bruising three-month campaign in which President Benigno Aquino III led efforts to discourage Filipinos from voting for him due to fears the mayor may endanger the country's hard-fought democracy.

"Let us be friends," Duterte said in a news conference after voting in southern Davao city. "Let us begin the process of healing."

In the unofficial count based on partial results transmitted electronically from voting centres nationwide, Duterte had more than 12.2 million votes, followed by Interior Secretary Mar Roxas with 7.0 million. Sen. Grace Poe had 6.9 million votes, and Vice-President Jejomar Binay was next with 4.1 million.

Sen. Ferdinand Marcos Jr. led with 11.1 million votes in an unofficial count of the vice-presidential race, followed by Rep. Leni Robredo, who had 10.4 million.

Vice presidents are elected separately from presidents in the Philippines.

"I am feeling that by all indications we should be successful today," Marcos said in a statement.

Aquino, the son of democracy champions who fought Marcos' dictator father, also campaigned against Marcos Jr., who has never clearly apologized for economic plunder and widespread human rights abuses that occurred under his father.

Weary of poverty, crime, corruption and insurgencies in the hinterlands, voters looked for radical change at the top.

Duterte, a 71-year-old former prosecutor, has peppered his campaign speeches with boasts about his Viagra-fueled sexual prowess and jokes about rape. But he also successfully tapped into the discontent, and many voters overlooked his unashamedly crude language.

"All of you who are into drugs, you sons of bitches, I will really kill you," Duterte told a huge, cheering crowd Saturday in his final campaign rally in Manila. "I have no patience, I have no middle ground, either you kill me or I will kill you idiots." Statements such as those have won him the nickname "Duterte Harry," a reference to the Clint Eastwood movie character "Dirty Harry" who had little regard for rules.

Duterte, who has been compared to U.S. Republican presumptive presidential nominee Donald Trump, threatened during the campaign to close down the Philippine Congress and form a revolutionary government if legislators stonewall his government.

That has alarmed the political establishment, which fears Duterte will squander the hard-won economic progress under Aquino. Aquino has called Duterte a threat to democracy, and likened him to Adolf Hitler.

Aside from the presidential and vice-presidential races, more than 45,000 candidates contested 18,000 national, congressional and local positions in elections that have traditionally been tainted by violence and accusations of cheating.

Duterte said he was satisfied with the conduct of the balloting. "So, far I have not received any reports of cheating and violation," he said.

At least 15 people were killed in election-related violence and more than 4,000 arrested for violating a gun ban, according to police.

About 55 million Filipinos registered to vote at 36,000 polling places across the archipelago of more than 7,100 islands, including in a small fishing village in a Philippine-occupied island in the disputed South China Sea.

In final campaigning Saturday, Aquino warned voters that Duterte could be a dictator in the making and urged them not to support him.

Filipinos have been hypersensitive to potential threats to democracy since they rose in a 1986 "people power" revolt that ousted Ferdinand Marcos.

On the campaign trail, Duterte offered radical promises, including his bold anti-crime pledge and a plan to sail to China's new artificial islands in the South China Sea and plant the Philippine flag there. The other candidates stuck to less audacious reforms.

Duterte's opponents have all accused him of making remarks that threaten the rule of law and democracy.

Financial market analysts are predicting that a Duterte win would weaken the Philippine peso given his uncertain economic platform.

The jitters have affected the Philippine stock market, which fell Friday -- the last day of trading before Monday's election holiday -- for the 10th time in 11 days.

"The market is obviously emotional and the stronger emotion is usually fear rather than hope," said Jose Vistan, research head at AB Capital Securities Inc. "A big chunk of the reason why we're behaving the way we are is obviously because of the elections."

"Duterte is completely out of the system, he's out of the box," said political science Prof. Richard Heydarian of De La Salle University in Manila, adding that in the mayor's portrayal of social problems, "there is a gap between the rhetoric and reality but it's working, it's creating panic among a lot of people and rallying them behind Duterte."

Duterte built a political name with his iron-fist approach to fighting crime in Davao, where he has served as mayor for 22 years. Human rights groups accuse him of carrying out extrajudicial killings to fight crime. During the campaign he joked about wanting to be the first person to rape an Australian missionary who was sexually abused and killed by inmates in a 1989 prison riot.

Aquino has a mixed record in his six-year term, which ends in June. He presided over an accelerating economy, which recorded one of the highest growth rates in Asia at an average of 6.2 per cent between 2010 and 2015. He also introduced new taxes, more accountability and reforms, including in the judiciary, and cracked down on tax evaders.

But more than a quarter of the Philippines' 100 million people remain mired in poverty, inequality is rampant and an immediate solution to decades-long Muslim and communist insurgencies in the south remains elusive.

Annual debt payments, some dating back to the Marcos years, and limited funds stymie infrastructure improvements and public services, including law enforcement, fueling frequent complaints.

Associated Press photographer Alberto "Bullit" Marquez in Davao, Philippines, contributed to this report