Duterte stated, "I'm going to destroy the Conservative Party, and Hernán Sánchez y Rodrigo. Read my lips, they are not going to mess with the Southern Philippines, the culture, lifestyles of the peoples of Mindanao, if they try, I'll meet them on the other side, they'll have police, constabularies and soldiers to be meeting face-on. Believe me, our law enforcement down here in Mindanao enforces justice, not the will of crooked politicians."
Duterte is a well-known southern Filipino politician, and his stance on southern nationalism in the Philippines is well-known. Though not a native of Mindanao, Duterte has repeatedly stated his intent to the live out the rest of his life as if a native of Mindanao, and serve the people of the south.
If one can recall in 2012, "I was born in Leyte, but I've gone native to the glorious island of Mindanao, and its vast colorful and diverse history. I will place myself among the peoples of Mindanao, whether they be Moro, Lumad, Visayan, Chinese or Malay, long live the south."
Despite running for presidency coming from a left-wing party, Duterte himself has evidently shown himself to be a nationalist and conservative for the south. A Methodist, he has been known for criticizing Roman Catholicism, the Spanish Inquisition, and symphatizing with Lumads and Moros. He befriended the Sultan of Sulu, though nothing more but a historical title as the sultanate no longer exists. It is Duterte that required Malay to be taught as a foreign languages in all public schools across Davao City and had earned the reputation of implementing the death penalty for anti-Moro and anti-Lumad militants in Davao City, as well as imprisoning those who dared to mess with southern Filipino culture.
His strict law enforcement is also well-known, a rumor has gone around that simply even spitting on the ground in Davao City will get you imprisoned and killed. Duterte is simply often-known as the "Sheriff" of the Philippines, and made plans to serve as the Governer-General of Mindanao.
Rodrigo Duterte also stated that he agreed with SNP leader Halima Abdullah's statement regarding Hernán's bid to run for the presidency in 2016.
He said, "I wholly agree with Halima Abdullah of the Southern Nationalist Party, and what she said about the Conservatives. They'll act like good constitution-abiding Filipinos for now, but just watch, if they install a president, that president will surely try to be our last. Their [Conservatives'] goal is to once more I shall repeat, destroy the sovereignty of the Philippines, destroy and oppress the native cultures of not only Mindanao, but also the Sulu Archipelago, Palawan and Cebu. Quite frankly, I'd actually like to see them try to install a prime minister under a king, the sheer outrage caused by it would likely form a resistance, and I will surely spearhead that resistance."
However though, Duterte's "southern" reputation was rather vastly damaged in 2015, in the wake of the Zamboanga City Shootings when he stated his support for the banning of Moro flags in the southern Philippines which he argues stands for hate and extremism. Duterte had introduced a bill that would ban Moro flags from Davao City, and make it punishable by imprisonment. However it failed, though Duterte still had the power to ban Moro flags from certain events in Davao City. This was evident when a Davao City police officer of Maguindanaoan ethnicity and Muslim faith was fired from the force, for flying a Moro flag on his squad car.