Former Supreme Court Associate Justice Antonio Carpio said the bloc led by Sen. Sherwin Gatchalian may validly elect a Senate president with 12 votes, arguing that Sen. Jinggoy Estrada should not be counted among the Senate's voting members because of his suspension under the Plunder Law.

In an interview, Carpio said Estrada's pending plunder case and preventive detention legally prevent him from exercising the powers of a senator, including voting in Senate proceedings.

“The 23 is the base number of senators for purposes of electing the Senate president. So a majority of 23 is 12,” Carpio said.

Carpio cited Supreme Court rulings, including Trillanes v. Pimentel, which held that a public official under preventive detention cannot hold public office while detained. He also pointed to Section 5 of Republic Act No. 7080, or the Plunder Law, which mandates the suspension of any public official charged with plunder while the case is pending.

“If you are suspended from office, that means you cannot exercise the functions and powers of that office. One of those functions and powers is to vote,” he said.

The former magistrate argued that the constitutional requirement that a Senate president be elected by “a majority of all the members of the Senate” refers only to senators who are legally qualified to vote.

“When the Constitution says the Senate president shall be elected by a majority of all the members of the Senate, all means all those who can vote. Those who are disqualified, you do not count,” Carpio said.

His position directly challenges the view advanced by senators aligned with Sen. Alan Peter Cayetano, who have argued that a majority of all 24 senators is required to elect a Senate president.

Carpio added that if President Ferdinand Marcos Jr. calls a special session during the congressional recess, the 12-member Gatchalian bloc, which includes Senate President Francis Escudero, could proceed with the election of a new Senate leader.

He also said Cayetano's camp may ultimately need to seek relief from the Supreme Court if it contests the legitimacy of the Gatchalian-led majority.