Philippine presidential candidate Manuel Roxas (right) at the event where President Benigno Aquino (left) formally endorsed him in Manila, July 31, 2015. Despite Aquino's backing, Roxas ranks fourth in many surveys. Reuters

Philippine presidential candidates attacked each other on experience and achievements in their first debate, with Manuel Roxas, the administration candidate, who is in fourth place, leading the offensive. The debate was held Sunday in Cagayan de Oro City in the southern Philippines and televised on the GMA TV network.

Roxas said Sen. Grace Poe, whose government service consists of two years as head of the film and TV classification board and less than three years in the Senate, would be doing the equivalent of on-the-job training if elected May 9. That was meant to contrast with his 20 years of service in the House of Representatives, Senate and three cabinet-level departments.

“The presidency isn’t OJT [on-the-job training],” Roxas said. “The futures, lives and progress of 100 million Filipinos are riding on this.” Referring to Poe, 47, whom he has admitted trying to get as his vice presidential candidate, Roxas, 58, said: “There is a right time for everything. How will you know if you are being duped? How will you choose between the recommendations of your cabinet secretaries?”

Poe said she knows when people are trying to dupe her. Then she turned Roxas’ resume — including stints in the Department of the Interior and Local Government and Department of Transportation and Communications, which supervises the Metro Rail Transit. Roxas was transport secretary from 2011 to 2012 and is still blamed for the department’s perceived failure to fix and expand the train and bus systems in Metro Manila, which Waze ranked the worst city in the world in traffic.

“He’s served 3 administrations, been given several responsibilities in government,” Poe shot back. “Forgive me, but I have investigated many things like the DILG, DOTC and MRT, and in my view, you don’t need a lot of experience to know the government’s help in transportation is lacking.”

Vice President Jejomar Binay piled on, hitting Roxas for his alleged failures as transport chief and then as head of the government’s preparatory and rescue effort for Typhoon Haiyan, which left more than 6,000 dead in 2013, mostly in Leyte island.

“The analysis-paralysis of Roxas’ time won’t happen with me,” Binay said. “I am a decisive and effective leader. I don’t go back and forth, delaying decisions,” he said, highlighting the slow roll-out of transport infrastructure. He then said Roxas has neglected Haiyan recovery efforts. “Where did he go? He disappeared. That’s why the people of Leyte are really angry with him, because of his failure.”

Binay and Poe have been rotating between the top two spots in most surveys since mid-2015, while Roxas and Davao City Mayor Rodrigo Duterte have held third and fourth place. Duterte, who has held no national office, became competitive as Filipinos took to his tough talk and tough reputation — including contradictory statements on whether he engaged in extrajudicial killings. During the debate, he said his administration would be “bloody,” as he solved crime and corruption in three to six months.

Later in the debate, Roxas went after Binay, after the vice president said he had licked illegal drugs in Makati, the rich city Binay and his family have ruled for 30 years. Roxas used that as cue to say developer Ayala Land Inc., not Binay, is responsible for Makati’s rise, as well as claim the city still has a lot of poverty and a drug problem.

“Isn’t the truth that here are two Makatis? The Makati of the Ayalas which is progressive and where there are many jobs, and the Makati of the Binays, which is still poor," Roxas said, then naming parts of Makati that Ayala Land didn't develop. "The poor are still there. The drugs are still there. In fact, Makati has the highest drug rate. All the rich, all the clubs, every Friday and Saturday, drugs flow in Makati.”

The bad blood between Roxas and Binay dates to at least 2010, when Binay came from behind to beat Roxas for the vice presidency -- Filipinos vote separately for president and vice president -- and intensified amid corruption allegations Binay supporters said were politically motivated. Meanwhile, some Poe supporters believe Roxas or his backer, President Benigno Aquino, is behind moves to disqualify her on citizenship and residency grounds stemming from her being a foundling who lived in the U.S. in her 20s and 30s, even taking U.S. citizenship.