Speaker Martin Romualdez did not mince words when he blasted former president Rodrigo Duterte on Monday over the former president's "budol-budol" or scam allegations against President Ferdinand Marcos Jr. and his alleged "conflicted" stance about Charter change.

"So, unless you have proof of your allegations behind your call to our beloved President Ferdinand R. Marcos to step down, better think first. Think first and bring out the proof. Because we know what you are saying is not true," said Romualdez, cousin of Marcos.

The House chief labeled the Dutertes' call for Marcos to resign from the presidency as premature and prodded the ex-president to show some respect to the 31 million Filipinos who put Marcos in power.

Duterte on Sunday threw allegations against Marcos and repeatedly called him "bangag" and "drug addict" at a prayer rally against Cha-cha in Davao City, which coincided with the Bagong Pilipinas kickoff rally at the Quirino Grandstand in Manila organized by Malacanang.

Duterte claimed he once saw Marcos' name on the Philippine Drug Enforcement Agency drug watch list when he was mayor of Davao. But PDEA, in a statement, said Marcos "is not and was never" part of its drug list.

On top of the accusations, Duterte also warned that Marcos might suffer the same fate as his father, the late Ferdinand Sr., who was ousted in 1986 by the Edsa People Power.

Singing the same tune, the ex-president's son, Davao City Mayor Sebastian Duterte, asked Marcos to step down from power if he had no "love" and "aspirations" for the country, accusing him of being "lazy and lacking compassion" for Filipinos.

Romualdez vehemently denied the "wild" allegations of the Dutertes, saying nothing can be farther from the truth.

"That's not true". Are you making a story again? Stop that scam [stories] from Davao," Romualdez said.

The Speaker also hit the senior Duterte over his opposition to Cha-cha, pointing out that, in fact, during his presidential campaign in 2016, Duterte had pushed for federalism as a new form of government.

"First of all, maybe President Duterte really struggled because the platform that made him win was federalism. It's not just the amendment of the economic provisions; it's the change of the entire government system," he said.

"It looks like he couldn't handle it. Now that there is a good move for charter amendments, maybe he sees that what he didn't do [before] will now happen, so he criticizes," Romualdez added.

Duterte alleged that the motive behind the people's initiative, one of the modes to revamp the Charter, was to reinforce Marcoses' control over power. He also accused Marcos' allies in Congress of plotting Charter reforms just to lift term limits.

Romualdez advised Duterte to exercise caution in his statements, as he may have much to answer for during his stint, such as his bloody anti-drug campaign.

"Let him think first. They say those who are in glass houses should not throw stones. Maybe he doesn't know; he has many shortcomings, right?," Romualdez said.

About 7,000 people were killed under Duterte's drug war, based on the government's data, the majority of whom were from low-income families.

Local and international human rights organizations, however, estimate the number to exceed 30,000.