DAVAO CITY (UPDATED) - Presumptive President Rodrigo Duterte will build a broad coalition of legislators to push for his agenda, including a shift to a federal-parliamentary system of government, his spokesman said Tuesday.

The tough-talking mayor expects members of other parties to either switch or align themselves with his own PDP-Laban, spokesman Peter Laviña told reporters.

“It is very normal in Philippine politics that members of Congress and the Senate to be friendly with whoever is in Malacanang,” Laviña said.

“Many of them even transfer political parties. We expect that. At the same time, we will try to reach out to everyone,” he said.

In what seems to be a sign of a budding coalition between former rivals, Senator Antonio Trillanes, who was very critical of Duterte during the campaign, offered a conciliatory tone.

In a press conference Tuesday afternoon, Trillanes said he will not block Duterte's agenda, especially if it will benefit the Filipino people.

"We will just have to give him the latitude to do his thing and watch and monitor from the sidelines and not be obstructionist. Then we will take it from there," Trillanes said.

"Pag maganda, lahat naman tayo, tulong-tulong kasi ang magbebenepsiyo dito ay ang taumbayan," he added.

Duterte will pursue a "major rewriting" of the three-decade-old Constitution to shift to a federal parliamentary form of government and ease foreign ownership restrictions on business, Lavina said earlier Tuesday.