Duterte has been mayor of Davao City on the southern island of Mindanao for two decades, where his strongman swagger and endorsement of the execution of criminals earned him the nicknames "Duterte Harry" and "The Punisher." He's been likened to U.S. presidential candidate Donald Trump, using populist rhetoric to reach Filipinos who feel the mainstream political parties are out of touch.
"Duterte's main asset is that rightly or wrongly many people see him as having led a 'Filipino life,' with all the frustrations and hardships that entails," said Stephen Norris, senior Southeast Asia analyst at Control Risks in Singapore. "To voters, it's conceivable that he would actually make a difference on traffic, crime and corruption from the top down, because he has done so locally."
The leadership in the Philippines has for decades been the realm of powerful families whose main assets are their wealth and dynastic connections. But the latest Pulse Asia Research Inc. survey shows Duterte, whose father was a lawyer and mother a teacher, holding a double-digit lead over the other candidates, which would see him take the presidency under a first-past-the-post voting system.
While President Benigno Aquino delivered average growth above 6 percent -- one of the fastest rates in the world -- and nearly 4 million jobs in his six year term, the stronger economy has also spurred frustration. Record car sales have clogged the already-gridlocked capital Manila, while infrastructure spending hasn't improved public transport. Graft, illegal drugs and crime are concerns of voters nationally, according to Pulse Asia, and poverty rates remain stubbornly high.
Often casually dressed in jeans and a polo shirt on the campaign trail ahead of the May 9 vote, Duterte's style is described by Institute of Southeast Asian Studies senior fellow Malcolm Cook as a mix of former New York City mayor "Rudy Giuliani, Donald Trump and Mad Max."
While his remarks resonate with voters, and the influential Philippine church Iglesia ni Cristo reportedly backed Duterte this week, investors are voicing concern over his lack of economic experience, plus suggestions he'll trade Aquino's fiscal discipline for spending on populist programs. Last month the peso slumped 1.7 percent, the worst performing currency in Asia, and stocks fell 1.4 percent.
"I hope when he does become president he'll be more grounded and less controversial," said Soo Hai Lim, a Hong Kong-based money manager at Baring Asset Management, which oversees about $41 billion. "His platform to reduce crime is good but at the end of the day investors need somebody who could implement policies that are generally good for the investment climate."
Duterte has sought to reassure business leaders, but he's also been unpredictable on the campaign trail and avoided specifics. He's pledged to keep spending on public transport and cash handouts to the poor, while identifying education and agriculture as priorities.
"Our best case scenario is that Duterte will be pragmatic in choosing his policies," said Euben Paracuelles, an economist at Nomura Holdings in Singapore. That would aid an economy underpinned by consumer spending, remittances and a booming business process outsourcing sector.
"If prudent fiscal and monetary policies remain, the Philippines can sustain growth of at least six percent under the next administration," said Luz Lorenzo, head of Philippine research at Maybank ATR Kim Eng in Manila. "How good the next government is in implementation will make the difference in how fast the economy grows."
Businessman Fervie Termulo, 35, is one voter in the staunchly Catholic nation of about 100 million people looking for a change. Termulo's life has improved in some ways under Aquino: The owner of an electronics repair shop has also become co-owner of a car wash shop, opened two barbecue stalls, and drives part-time for Uber Inc. He's tripled his income to $640 a month, well above the minimum wage.
Yet his wife was robbed at knife-point two years ago in their home province north of Manila, and Termulo says petty theft and drug abuse have risen. "I want these criminals to be stopped and Duterte is the man for the job," he said. "I don't know how he will do it but I believe in him."
Accusations from groups such as Human Rights Watch that Duterte's advocacy of extra-judicial killings led to the deaths of more than 1,000 suspected criminals since the late 1990s have not dented his approval rating.
"Duterte is tapping into a few key sentiments," said Greg Poling, a Southeast Asia specialist at the Center for Strategic and International Studies in Washington. "In a country with persistently high violent crime, his tough talk and track record in cutting crime as mayor of Davao are attractive to many people, even if his methods were deeply troubling."
As Duterte rises the previously favored candidate, Senator Grace Poe, has faded and she also trails Aquino's nominee Mar Roxas, with Vice President Jejomar Binay polling fourth. Poe and Roxas were named as the best to steer economic policy in a Bloomberg survey of economists.
Duterte's tough-guy rhetoric has pushed the boundaries. When declaring his candidacy last year, he advised "people to put up several funeral parlor businesses" to deal with a looming pile of dead drug traffickers. He later pledged to kill 100,000 criminals and feed their bodies to the fish in Manila Bay.
In a radio interview in December he admitted to helping kill at least three suspected rapist-kidnappers during a rescue operation in Davao in 1988. "I said 'Put your hands up'. No one did, so I attacked." Duterte said he fired two magazines from his gun but denied committing a crime, saying he was trying to stop it as a "person in authority."
Having portrayed himself as a man who lives modestly, he's faced accusations over his wealth. Senator Antonio Trillanes, a vice-presidential aspirant supporting Poe, accused Duterte of failing to declare assets of 2.41 billion pesos ($51 million) across 17 accounts over nine years.
"I am not a rich man," Duterte said on April 27. "I have never stolen. Don't believe what others are saying. That's pure garbage."
He's also unnerved other countries, spurring criticism from Australia after he told supporters at an event he should have been first in line for a turn when an Australian missionary was gang raped in 1989. He said later that's just the way he speaks, though his camp issued an apology.
Duterte has also wavered between threatening China over their territorial dispute in the South China Sea, to pledging to hold talks.
His disdain for the machinery of government -- he has vowed to abolish Congress if it stands in his way -- has raised concerns of a return to the era of former dictator Ferdinand Marcos. Marcos' son Senator Ferdinand Marcos Jr. is in the race for the vice-presidency under the Philippines' split-ticket voting system.
Duterte may use executive orders to try to expand his powers if he wins, said Cook from ISEAS. "That would lead to more political uncertainty and conflict between different arms of government. If he tries to overstep, the Supreme Court would try to limit that."
