Malacanang said on Monday there could be a tactical alliance among Supreme Court Chief Justice Maria Lourdes Sereno, Ombudsman Conchita Carpio Morales and the opposition Liberal Party to oust President Rodrigo Duterte.

In a press briefing, Presidential Spokesperson Ernesto Abella said the action being taken by these parties, particularly the Ombudsman, was suspect.

Duterte on Saturday night challenged Carpio and Sereno to resign with him.

"Well, it’s his prerogative to make that call. The President believes the Supreme Court Justice and the Ombudsman have allowed themselves to be used by certain political forces to discredit him and his administration in order to spark public outrage and eventually oust him from the Presidency," Abella said.

"In other words, he finds them suspect. And it is his prerogative to ask them to resign," he added.

Asked if LP, the Ombudsman and the Chief Justice were having a tactical alliance to oust the administration, Abella said, "May be in effect, that seems to be the implication."

The Ombudsman has been conducting an investigation against Duterte and his family for their alleged undeclared wealth following a complaint filed by opposition Senator Antonio Trillanes IV.

Duterte, in the same speech on Saturday, has claimed Sereno of being corrupt.

Abella said at the "right time and as necessary," the president would come out with evidence to back up his claim against Sereno, who is now facing an impeachment complaint at the House of Representatives.

The LP is the political party of former President Benigno Aquino III and detained Senator Leila de Lima, also Duterte's staunch critic. Celerina Monte/DMS