Senate Minority Leader Aquilino "Koko" Pimentel III on Monday said the House of Representatives' plan to amend the 1987 Constitution without involving the Senate is "impossible."

"Not involving the Senate, and they believe that they can amend the Constitution? Impossible. It is not only unconstitutional but also impossible," said Pimentel in a television interview.

Last week, Speaker Martin Romualdez bared the House of Representatives' plan to amend the Constitution next year without mentioning the involvement of the Senate.

Romualdez said the push for charter change next year will focus on removing the "restrictive" economic provisions in the current charter. He noted that revisiting the 1987 Constitution "would be our legacy in the 19th Congress."

However, Pimentel said that such a move would further turn senators cold to the proposed charter change.

"They should not do that. You amend the Constitution first. Even the procedure in amending the Constitution, you have to amend it properly rather than just doing it as if it has been amended," he said.

"If that is the attitude of our friends from the House, and they really announced that, all the more they will really [not get] the support of the senators," he added.

The 1987 Constitution provides three ways to change the Charter: Through a constitutional convention, a constituent assembly, or a people's initiative.

Last March, the House of Representatives approved House Bill 7352, which calls for a constitutional convention or con-con to amend the Constitution.

This, however, did not progress as the Senate declined to entertain such a move, stressing that the measure did not the blessing of  President Ferdinand Marcos Jr.

Senator Robin Padilla's recent call for charter change via a constituent assembly or con-ass has suffered the same fate as his fellow senators remain cold to the measure.