Despite his strong anti-corruption policy, President Rodrigo Duterte has to endorse the senatorial bid of daughter of late dictator Ferdinand Marcos, Ilocos Governor Imee Marcos, out of gratitude, Malacanang said on Monday.

Presidential Spokesperson Salvador Panelo defended Duterte's support on the candidacy for senator of alleged plunderer former Senator Jinggoy Estrada, saying he is "innocent until proven guilty."

"According to the President, he is helping Imee because he is indebted to her," he said, noting that in Duterte's previous speeches, he kept on saying Imee was only one of the two governors in the country who supported him in his presidential bid in 2016.

"I think the reason is 'debt of gratitude'," he said.

As for Jinggoy, son of former President and Manila Mayor Joseph Estrada, a convicted plunderer, Panelo said he is not yet convicted for plunder charges he is facing before the Sandiganbayan anti-graft court.

Estrada allegedly pocketed multi-million pesos from his pork barrel when he was a senator.

"Former Senator Estrada is charged with corruption and the Constitution says unless you are convicted with a final judgment, you are presumed innocent. So the assumption is Estrada is innocent," Panelo said.

He said Jinggoy has been granted temporary liberty after posting bail since evidence of guilt against him was not strong.

Duterte has fired several government officials, including Cabinet members, by mere allegations they were engaged in corruption.

He has said he would not tolerate even a "whiff" of corruption.

So far, the Palace has not pursued charges against those officials who were fired due to alleged irregularities.

There were other officials who were allegedly involved in corruption, but they were just pressured to resign and to be appointed to another government post again.

Duterte has expressed support for the senatorial bid of his former close aide Christopher "Bong" Go, former Philippine National Police chief Ronald dela Rosa, and former political adviser Francis Tolentino.

Duterte has yet to name seven other senatorial candidates to complete the 12 slots for the May midterm elections. Celerina Monte/DMS