The Liberal Party (LP) on Thursday called on Senate President Aquilino Pimentel III to uphold the independence of the Senate.
This comes, after President Rodrigo Duterte linked Senator Leila de Lima to illegal drug trade.
"We call on the Senate President to uphold the independence of the Senate whose membership must always be vigorously supported as they fulfill the people's mandate to make inquiries in aid of legislation," the LP said in a statement.
The LP shot back against President's tirades against the senator, whom he called an "immoral woman" and an "adulterer."
The LP said, "nakakalungkot ang mga salita at mga paratang na naninira sa kaniyang pagkatao at lingkod bayan."
It added, "Senator Leila de Lima is doing her job as a senator of the Republic. She deserves support, not condemnation; respect and not gutter language. She and our people deserve the facts, not innuendo."
In a speech at the Philippine National Police Headquarters at Camp Crame on Wednesday, President Rodrigo Duterte accused a female senator of involvement in drug trade, claiming that she had used drug money collected by her "driver and lover" on her behalf for the campaign.
Later, he identified Senator Leila de Lima as the person he was referring to.
De Lima had called for a senate investigation on the spate of killings relating to the campaign against illegal drugs.