Senators crossed party lines to reject Malacañang's insistence on charter change before the 2010 elections.

President Arroyo's sudden espousal of federalism, purportedly to bring about peace in Mindanao, is also causing some pro-federalism senators to rethink their support for Joint resolution 10 filed by Senate minority leader Aquilino Pimentel Jr. and supported by at least 11 other senators.

Pimentel's Joint Resolution 10 seeks to convene Congress into a constituent assembly (Con Ass) for the purpose of revising the constitution to establish a federal system of government.

Opposition Sen. Panfilo Lacson broadly hinted Wednesday he might withdraw his signature from resolution 10.

"Ako, in favor of federalism, pero kung gagamitin ng Malacañang for their own selfish agenda, baka dapat maghinay-hinay muna kami," Lacson said. "Nagaalala ako bakit sinasakyan nila bigla ang federalism. Malinaw from the start na gusto nila manatili beyond 2010."

Lacson said senators should first discuss the implications should they begin committee hearings on Joint Resolution 10. 

"Kung nag-start ba kami ng hearing o discussion sa floor, yun na ba ang start ng Con Ass? Yan ang dapat pag-aralan," he said.

Even administration Sen. Juan Miguel Zubiri said charter change before 2010 might be a "difficult pill to swallow", in light of suspicions it is a ploy to extend President Arroyo's term.

"The question is timing. Marami nagtatanong: vehicle ba ito para patagalin ang administrasyon sa kanyang pwesto? Kami sa Senado, the consensus is, if there would be any amendment it should be after 2010," Zubiri said.

He also hit back at presidential spokesman Jesus Dureza who said flip-flopping would be blamed on the Senate for the failure of charter change for federalism.

Zubiri said Malacañang was just looking for scapegoats for its mistakes in the aborted GRP-MILF (Government of the Republic of the Philippines-Moro Islamic Liberation Front) Memorandum of Agreement on Ancestral Domain, which was kept secret from the Senate.

"For them to deny us that information, and for them to say we are to blame if federalism does not succeed is grossly unfair," he said.

Asked to comment on Malacañang's announcement that "it's all systems go for cha-cha",  administration Sen. Richard Gordon said:  "In their mind. Because the way I look at it, di talaga uubra na magkaroon tayo ng cha-cha ngayon sapagkat yung sinasabi na magkaroon ng federalism, tumayo nga agad ako kahapon at sinagot ko yun. Sabi ko, pabor ako sa federalist government, pero di tayo dapat magbago ng Constitution until after 2010."