MANILA – President Rodrigo Duterte is confident that his toughest critic, Senator Leila de Lima, will eventually go to jail.

Duterte has accused De Lima of allowing the illegal drug operations of convicts at the New Bilibid Prison (NBP) to flourish when she was justice secretary during the previous administration.

• READ: Duterte's 'drugs matrix' tags De Lima, others

“Makukulong talaga iyan, sigurado yan, because of the testimonial evidence. [She will be jailed, that's for sure, because of the testimonial evidence.],” Duterte said.

Duterte also chided Filipinos who voted for De Lima.

“You elected a senator, kayong mga Pilipino, who was into narco-politics, who was being financed from the inside… [by] the convicts inside the prison,” he said.

Several drug convicts and NBP gang leaders have testified in a lower House probe that De Lima received money in exchange for allowing their illegal activities to continue.

The recurring accusation from the convicts who testified before the House probe was that De Lima received drug money from convict Jaybee Sebastian, who allegedly cornered the drug trade at the Bilibid through the help of the then-justice secretary.

• De Lima: Gov't asset si Jaybee Sebastian

Addressing allegations he coddled Sebastian and his illegal activities, De Lima last week said Sebastian was the government's “asset” in Bilibid, which is why she did not order the latter’s transfer to the National Bureau of Investigation (NBI) detention center in the wake of the crackdown at the national penitentiary.

For Duterte, it is odd for De Lima to be using a convict as an asset.

“Why would you have an asset such as Jaybee Sebastian? Do you not trust the NBI, the military men?” he said.

De Lima has denied all the allegations of Duterte and his allies, saying the witnesses were tortured to testify against her.

She believes that she is being politically persecuted because of her criticism of extra-judicial killings in Duterte's war on drugs.

De Lima pointed out, the very same convicts who supposedly raised a P1 billion bounty to have Duterte assassinated, suddenly became the witnesses of the government against her.