ISLAMABAD, Pakistan — The humanitarian and economic disaster caused by the worst floods in Pakistan's history could spark political unrest that could destabilize the government, dealing a major blow to the Obama administration's efforts to fight violent Islamic extremism.

The government's shambling response to floods that have affected a third of the country has some analysts saying that President Asif Ali Zardari could be forced from office, possibly by the military, which has ruled Pakistan for more than half its 63-year history.

Other experts caution that the state itself could collapse, as hunger and destitution trigger explosions of popular anger that was already seething over massive unemployment, high fuel prices, widespread power outages, corruption, and a bloody insurgency by extremists allied with al Qaida.

"The powers that be, that is the military and bureaucratic establishment, are mulling the formation of a national government, with or without the PPP (Zardari's ruling Pakistan Peoples Party)," said Najam Sethi, the editor of the weekly Friday Times. "I know this is definitely being discussed.