MANILA -- The House of Representatives may have speedily approved Resolution of Both Houses No. 6, which seeks to amend the 1987 Constitution via “hybrid” Constitutional Convention, but Senate President Juan Miguel Zubiri said such pace should not be expected in the chamber.

• Zubiri: I don't understand House rush for charter change

Zubiri pointed out that entertaining Charter change debates could even result to the entire revision of the Constitution and forming of a unicameral parliamentary form of government.

"Kung unicameral na po tayo, unicameral parliament, you think pwede natin malagyan ng preno ang mga panukala na controversial, let's say tax measures, additional tax measures na dagdagan ang buwis ng ating mga kababayan,” Zubiri said during an interview with ANC’s “Headstart” program.

He added: “I really believe in the sanctity and the wisdom of having a Senate, a bicameral system of government. And if it means my head then so be it, so be it, but not on my watch, where I'm sitting here.”

Zubiri, however, was quick to clarify that he is not stopping Sen. Robin Padilla’s Cha-cha public consultations.

• Padilla shrugs off colleagues' objection to Charter change

The problem, he explained, is coming up with the needed 3/4 votes in the Senate to pass the Charter change proposal.

“I don't think we have 18 votes to dance the Cha-cha, hindi kami makasayaw, wala kaming numero para malaman ng taumbayan. 18 boto ang kailangan ng ating mga kasamahan sa Senado para umusad ang Charter change, wala kaming numero na ganyan. So for us, it's moot and academic. We might as well focus on the LEDAC priority measures, which will help solve the problem of inflation, smuggling,” Zubiri said.

In an earlier interview, Sen. JV Ejercito said that only “4 to 5” senators are in favor of Charter change.

Senate sources named the five as: Senators Padilla, Francis Tolentino, Ronald dela Rosa, and Christopher Go of PDP-Laban, and Senator Mark Villar of Nacionalista Party.

• Lawmakers wary 'cha-cha' may include political amendments

Tolentino has already said that their party has yet to discuss the Cha-cha issue.

Go meantime underlined the need to be cautious.

ABS-CBN News tried to get Villar’s statement, to no avail.

Dela Rosa meanwhile admitted he is among the senators supporting Charter change, but only for economic amendments.

He, however, opens the possibility of eventually voting against Cha-cha if the majority disapproves the proposal.

Dela Rosa will be joining Padilla’s consultation hearing in Cebu on Friday.