MANILA - (2ND UPDATE) Senate President Aquilino "Koko" Pimentel III said Monday he stepped down as leader of the chamber and that he wished his successor, Majority Leader Vicente "Tito" Sotto III, well.

In his speech, the outgoing senate leader said he was grateful to have held the post of his father, former Senate President Aquilino "Nene" Pimentel Jr.

"He (elder Pimentel) served the Senate with dignity, staying true to his principles and consistently putting the interest of our nation before his and it was his example I tried to emulate during my time at the helm of the Senate," he said.

"I wish my successor, Senator Sotto, good health and godspeed and pledge to help the new leadership pass new pro-people legislation consistent the legislative agenda of the President," he added.

Pimentel stepped down after 15 majority bloc senators last week agreed to move for the change of Senate leadership.

"This is an example of a peaceful and willing transfer of power in the Senate," he said.

"Ang sinabi ko kay (I told) Senator Sotto, we will implement this change with the minimum disruption."

The Senate majority, he added, would meet later in the day.

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Pimentel said he will leave the new Senate president to decide on what Senate committee will be given to him.

He added that he will also continue going around the country to promote the shift to a federal form of government championed by PDP-Laban party chaired by President Rodrigo Duterte.

"The cause of federalism needs help. Federalism is not only PDP-Laban’s advocacy but also my personal one. I will go around the country, only personal time, to help explain to the people what federalism is all about and how the country will benefit from it,” he says.

Malacañang thanked Pimentel for his leadership of the Senate and noted that it respects the chamber's choice of leader.

"We respect the choice of our senators on their leader, although we would like to commend and express our appreciation also for the partnership we had with Senate President Koko Pimentel," Presidential Spokesperson Harry Roque said in a press briefing Monday.

"Whoever the senators may choose as their Senate president, we assure the incoming Senate president of our willingness to work with him as we recognize that whoever the new Senate president would be would also be a close ally of the Palace," he added.

Pimentel was elected Senate leader in 2016 at the start of the 17th Congress. He is also president of the ruling PDP-Laban party.

• Pimentel puts re-electionists in own PDP-Laban Senate lineup

Sotto, meanwhile, has campaigned against illegal drugs since he entered first politics as vice mayor of Quezon City in 1998, during the height of his career as an actor and musician.

As vice mayor, Sotto founded and organized the Quezon City Anti–Drug Council, which had been replicated in many local government units, according to his profile on the Senate website.

In 1992, Sotto began his 2-decade Senate stint, during which he served as minority and majority floor leader.

He also chaired the Senate committee on illegal drugs and led the Dangerous Drug Board as chair from July 2008 to November 2009.

In 2012, Sotto became controversial over plagiarized speeches.

• Kennedy to Sotto: Acknowledge you plagiarized dad's words

-- With reports from Dharel Placido and Sherrie Ann Torres, ABS-CBN News