MANILA — Senator Mark A. Villar on Thursday crossed the aisle to join the Senate majority, expanding the bloc's control of the chamber to 14 members against 10 in the minority.

The transfer hands the majority an additional member to advance its legislative agenda. Mr. Villar takes over the Public Works committee and secures a seat on the Commission on Appointments, the body that vets and confirms key presidential appointments. Committee chairmanships carry added weight in the chamber because bills generally clear committee before reaching the Senate floor.

Senate Majority Leader Juan Miguel F. Zubiri confirmed the move in a Viber message, saying Mr. Villar wanted to become more productive as a lawmaker.

Mr. Villar replaced Senator Vicente C. Sotto III as chairman of the Public Works committee, while Mr. Zubiri gave up his own seat on the Commission on Appointments to accommodate him. Mr. Sotto said the reshuffle would help the majority handle its legislative workload.

Mr. Zubiri said the bloc did hold a vote on Mr. Villar's admission, describing the move as "welcoming back a member of the majority."

"Senator Mark has always been with the majority anyways, from the very beginning," he told reporters. "When we started, he had just transferred to the minority. We had a heart-to-heart discussion with Senator Mark. He really wants to work."

The Senate leader denied that political considerations influenced the transfer, including the 16 votes needed to convict Vice-President Sara Duterte-Carpio in her impeachment trial. Senators, he said, would decide how to vote based on the evidence presented during the proceedings.

The realignment leaves the minority bloc, led by Senator Alan Peter S. Cayetano, with 10 members — four of whom are unable to participate in Senate proceedings. Senator Ronald M. dela Rosa remains in hiding, while Senator Loren Regina B. Legarda is on medical leave. Senators Rodante D. Marcoleta and Jose "Jinggoy" P. Ejercito Estrada, Jr. are detained. With those four sidelined, six senators are left to carry the minority's participation in day-to-day proceedings.

In a statement, Mr. Cayetano said the minority would continue its role in scrutinizing government policies and holding the administration accountable despite Mr. Villar's departure. He wished the senator well but noted that President Ferdinand R. Marcos, Jr.'s administration had made clear since May 11 that it wanted a closely allied working majority in the Senate.

Mr. Cayetano briefly served as Senate president after a leadership change on May 11 before Senator Sherwin T. Gatchalian replaced him on June 17.

Senator Christopher Laurence T. Go, a member of the minority, said he respected Mr. Villar's decision to switch blocs. On the majority side, Senator Raphael T. Tulfo said he learned of the transfer only on Thursday and welcomed Mr. Villar to the group.

Mr. Zubiri declined to say whether other minority senators had expressed interest in joining the majority.

"They're all welcome," he said. "All the members of the minority are welcome to join the majority."

Source: BusinessWorld, by Francessca S. Abalos — Villar joins Senate majority, boosting bloc to 14 as minority shrinks to 10 seats