It will be impossible for President Rodrigo Duterte not to endorse any presidential candidate in the 2022 elections, Malacanang said on Monday.

Presidential Spokesperson Harry Roque made the statement after Antonio Contreras, a political science university professor, suggested that it would be better for Duterte not to endorse anyone and just to be a father to politicians and for him not to run for vice president in order not to further divide the nation.

"Never that it happened in the Philippine history. From the time of (Emilio) Aguinaldo up to the time of (late President Benigno) Noynoy Aquino (III), it never happened that the president did not endorse the next president," he said in a television interview.

"I think Professor Contreras is asking for the impossible, if he's asking (that the President) will not endorse," Roque said.

But if the call is for Duterte not to run for vice president, he said it would be up to the President.

He said Duterte has mentioned that he would only run for vice president if needed.

Duterte's allies in Partido Demokratiko Pilipino-Lakas ng Bayan have urged him to run for vice president in next year's elections. Celerina Monte/DMS