Manila, Philippines (CNN) Rodrigo Duterte, whose outspoken commentary -- including joking about the rape of a missionary -- drew international attention to the Philippines' national elections, appeared poised to win his country's presidency Monday after a top rival conceded.

Grace Poe made the concession Monday night, according to CNN Philippines, even though formal results will not be announced until June.

Early exit polls had shown Duterte, the mayor of Davao City, leading with 38.92% of the votes counted, compared with Poe's 22.14%, according to the Commission on Elections.

"I congratulate Mayor Rodrigo Duterte, and I promise to join in the healing of our nation and to unify our countrymen for our country's progress," Poe said, according to CNN Philippines . Poe is a popular senator who was challenged over her citizenship

Earlier Monday, Duterte -- who sparked outrage at home and abroad over rape jokes and threats to kill criminals -- didn't appear worried about the election results. He boasted he hadn't even been following the race and instead had been fast asleep.

"You know, a lesson in life (is) there are things beyond your control," he said. "You can't control buying (of votes) and intimidation, we'll just leave it up to the police," he told reporters in a mix of Filipino and English.

Voters -- 55 million of the 100 million-strong population registered for the pivotal election -- braved stifling heat to cast their ballots.

What's up for grabs?

Tens of thousands of elected positions are at stake, from the presidency and his or her deputy as well as half the Senate and all of the House of Representatives to a huge number of local posts, ranging from governors and mayors to members of the provincial councils.

Photos: Philippine voters head to the polls A street in suburban Manila, the capital of the Philippines, is covered in campaign posters. Polls opened nationwide on Monday, May 9, 2016. Hide Caption 1 of 13 Photos: Philippine voters head to the polls Filipino voters check the voters' list as they queue up to cast their choice for the presidential elections in Davao City in southern Philippines on May 9, 2016. Hide Caption 2 of 13 Photos: Philippine voters head to the polls Crowds gather in front of a polling station on May 9, 2016. Millions of voters are expected to troop to polling precincts all over the country to elect the successor to President Benigno Aquino III. Hide Caption 3 of 13 Photos: Philippine voters head to the polls People fill out ballots on Monday, May 9, 2016. The front-running presidential candidate is the foul-mouthed, crime-busting mayor Rodrigo Duterte. Hide Caption 4 of 13 Photos: Philippine voters head to the polls Eighty-year-old Dioleta Esteban is assisted as she votes at a polling center in suburban San Juan, east of Manila, Philippines on Monday, May 9, 2016. Hide Caption 5 of 13 Photos: Philippine voters head to the polls Esteban shows the indelible ink on her finger after casting her vote. Hide Caption 6 of 13 Photos: Philippine voters head to the polls Boys distribute election leaflets outside a polling precinct in Davao City on May 9, 2016. Hide Caption 7 of 13 Photos: Philippine voters head to the polls Voters had to bear the stifling heat and long lines at some polling stations. Hide Caption 8 of 13 Photos: Philippine voters head to the polls Presidential candidate Grace Poe votes at a polling center in San Juan, east of Manila, on May 9, 2016. Hide Caption 9 of 13 Photos: Philippine voters head to the polls Presidential candidate and current Philippine Vice President Jejomar Binay (right) inserts his ballot into the vote counting machine inside a polling center at the San Antonio National High School in Makati, Philippines on May 9, 2016. Hide Caption 10 of 13 Photos: Philippine voters head to the polls Workers check computers at the command center of the church-backed election watchdog Parish Pastoral Council for Responsible Voting (PPCRV) in Manila, Philippines on the eve of election day, Sunday, May 8, 2016. Hide Caption 11 of 13 Photos: Philippine voters head to the polls An election worker carries official ballots as they are distributed to polling centers in the suburban Quezon City, north of Manila on May 8, 2016. Hide Caption 12 of 13 Photos: Philippine voters head to the polls People search for their names and their polling precincts on May 8, 2016. Hide Caption 13 of 13

Who were the main candidates?

Besides Duterte, 71, and Poe, 47, other presidential candidates include Miriam Defensor Santiago, 70, a longtime lawmaker and legal expert who contested the presidency in 1992; Vice President Jejomar Binay, 73, a close friend of former President Corazon Aquino's; and Interior Minister Mar Roxas, 57.

Photos: The candidates – Five candidates are contesting the 2016 Philippines presidential elections. From left to right: Jejomar Binay, Rodrigo Duterte, Miriam Defensor Santiago, Grace Poe and Manuel 'Mar' Roxas. Hide Caption 1 of 6 Photos: Rodrigo Duterte – Rodrigo Duterte has cursed the Pope, 'joked' about the rape of an Australian missionary, and been accused of involvement in extrajudicial killings while mayor of Davao City. Despite the headlines,

the major presidential polls show that around one in three Filipino voters want him as president, making him a clear favorite. Hide Caption 2 of 6 Photos: Grace Poe – Grace Poe, the popular daughter of the late Filipino action star, Fernando Poe Jr., started out as the front-runner but was formally disqualified by the electoral commission in early December 2015. Poe defeated the ruling in the Supreme Court of the Philippines in March 2016, but now faces an uphill battle to regain popularity. Polls presently place her in second place behind Duterte, with between 22-24% of the vote. Hide Caption 3 of 6 Photos: Currently Vice President of the Philippines, Jejomar Binay's run for the highest office has been marred by serious allegations of corruption. A March 2016 Philippines Commission on Audit report recommended that he be punished for a wide array of offenses with removal from office, although that can only be implemented through impeachment proceedings or by Philippine court proceedings. Binay slipped from third to fourth place in the latest SWS polls, with an estimated 14% of the vote. Hide Caption 4 of 6 Photos: Manuel 'Mar' Roxas – Manuel 'Mar' Roxas, grandson of former Philippine President Manuel Roxas, is a well-known local politician who serves in the Philippines senate. An investment banker in New York prior to returning home to run for office, the former Interior Secretary has overtaken Binay for third place in the most recent SWS poll, with support from 19% of respondents.

Hide Caption 5 of 6 Photos: Miriam Defensor-Santiago – Miriam Defensor-Santiago is a long time civil servant and notable for having served in all three branches -- judicial, executive, and legislative -- of government. However, she was forced to take nearly six weeks off from the campaign scene due to her battle with stage four lung cancer, not helping her position -- she has consistently placed at the bottom of multiple race surveys. Hide Caption 6 of 6

Why is Duterte so controversial?

In Davao City, where Duterte has held office for decades, he has long been dogged by allegations of ties to death squads and extrajudicial killings.

In April, a YouTube video surfaced appearing to show him joking about the 1989 rape and murder of an Australian missionary in Davao City. He later described it as "gutter language" but refused to apologize.

In his last campaign stump Saturday, Duterte played his role to the hilt and again vowed to butcher criminals as he told thousands in central Manila: "Forget the laws of human rights."

"If I make it to the presidential palace, I will do just what I did as mayor. You drug pushers, hold-up men and do-nothings, you better go out. Because as the mayor, I'd kill you," Duterte said to wild cheers from supporters.

He's threatened to bypass or even shutter Congress, leading to outgoing President Benigno Aquino calling for all the candidates to unite against Duterte, warning of uncertainty and the "specter of dictatorship" if he won.

Duterte has also promised to jail the corrupt, along with rogue members of the police and the military.

What's at stake for Filipinos?

The Philippine economy has steadily grown since the early 2000s, earning credit ratings upgrades, with spending power fueled by money sent home by an army of overseas workers.

On the political and diplomatic front, the government has been feted for standing up to China over a row in the South China Sea.

Ramon Casiple, a political analyst and head of the Institute for Political and Electoral Reform, said Duterte is "a protest vote."

"He is a symbol for the people. Nothing happened for many people in the past six years, and he has capitalized on his image as the folk hero here," Casiple told CNN.

How did voting progress?

Allegations of cheating were rampant around Manila and its southern suburbs.

One woman voter, who declined to be identified, said people representing themselves as allied to a certain politician offered her up to 3,000 pesos ($64) for a vote.

"I declined politely but I know of some who took the money. They were supposed to report back (to the people who offered the bribe) to collect the money," the woman said.

Scattered incidents of election-related violence caused five deaths in the southern province of Maguindanao, the Army's Sixth Infantry Division told the country's state-run Philippine News Agency.

Capt. Jo-Anne Petinglay said the polling remained generally peaceful and civilian casualties were low compared with past elections in the province.