MANILA (UPDATE) - President Rodrigo Duterte has designated Vice President Leni Robredo to be his partner in his drive against illegal drugs.

In a letter dated October 31, 2019, Duterte, through Executive Secretary Salvador Medialdea, asked Robredo to lead the campaign against illegal narcotics.

"I am pleased to transmit herewith your designation letter, signed by President Rodrigo Duterte, as co-chairperson of the inter-agency committee on anti-illegal drugs (ICAD)," the letter read.

Malacañang said it hopes the move would allow "detractors and critics" to "see the sincerity of the President in making such offer to the Vice President."

"Understand that the Chief Executive's ultimate motivation in making the same is the welfare of the Filipino people, with the hope that the government be successful in combating the atrocity caused by the use and trade of illegal narcotics," Malacañang said.

As of posting, Robredo has yet to issue a statement.

Last month, Robredo had called on Duterte to allow the United Nations to investigate his war on drugs which she said was “obviously, not working,” prompting Malacanang's challenge for her to lead the drug war.

She later clarified that she meant to urge administration leaders to "step back and assess" the narcotics crackdown.

Presidential spokesperson Salvador Panelo said he hopes Robredo would accept the Cabinet position, which he described as a "ladder to the presidency."

• Duterte giving Robredo a 'ladder to presidency' in drug czar appointment: Palace

"She should not listen to her colleagues who don’t want her to succeed. We’re giving her a ladder to the presidency. This is her chance, this is her moment," he told ANC.

"She should accept it. Be in the moment, help the Filipino people, help this country and help herself. And show her colleagues that she can do it."

Sen. Leila de Lima on Saturday said Duterte's offer to Robredo to lead government’s narcotics crackdown is just a "silly trap."

• De Lima believes ‘drug czar’ offer to Robredo a ‘trap’ meant to ‘shame’ VP

The Philippine Drug Enforcement Agency, which leads the ICAD, meantime welcomed Robredo's appointment.

• PDEA chair: Robredo can focus on rehabilitation, reintegration of drug users

"We believe that she can well contribute as a good leader, particularly on the advocacy cluster and rehabilitation and reintegration cluster," said PDEA chief Aaron Aquino said.

"By designating her as co-chairman of ICAD, it will greatly help and it’s nice to see when everybody’s working together."

The Philippine National Police said it would extend its "utmost courtesy, cooperation and full assistance" to Robredo.

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- With reports from Pia Gutierrez, ABS-CBN News