ISLAMABAD: Pakistan's President Asif Ali Zardari is facing mounting pressure to relinquish many of his powers, raising the spectre of a damaging political fracas just as the nation battles the Taliban.

Only 15 months into his rule, Zardari is contending with rock-bottom public opinion, strained relations with the powerful military, a bloody Islamist insurgency and a vocal opposition party challenging his rule.

He has lost much of the public sympathy that helped his Pakistan People's Party (PPP) win elections in early 2008, soon after the assassination of his wife, the hugely popular two-time prime minister Benazir Bhutto.

Political tensions that have simmered for months bubbled to the surface over the weekend, when a legal amnesty protecting Zardari and key aides from corruption cases expired, plunging the nation into uncertainly.

"At this point of time when the country needs undivided attention to face its challenges, the government could get entangled in legal battles and their future is so uncertain," said independent political analyst Talat Masood.

The corruption amnesty, known as the National Reconciliation Ordinance, was passed by former military ruler Pervez Musharraf in 2007.

It quashed charges against Zardari, Bhutto and other politicians in an gesture of political reconciliation as Musharraf faced increasing pressure to end nearly nine years of military rule and restore democratic elections.

Zardari spent several years in jail for corruption and is still referred to as "Mr Ten Percent" because of his reputation for taking kickbacks on deals.

Succeeding Musharraf as president in September 2008, Zardari has immunity from prosecution. But that immunity could now be challenged in the Supreme Court, opening the door for prosecution on outstanding cases.

Rasool Bakhsh Raees, a professor of political science at Lahore University of Management Sciences, said there were numerous grounds for challenging his immunity. And with so many foes, Zardari's position looked perilous.

"The legal process is going to take its course, and if it does I see slim survival chances for the PPP leadership including President Zardari," he said.

Weathering the storm will take political savvy on Zardari's part.

The president on Saturday gave control of Pakistan's nuclear arsenal to Prime Minister Yousuf Raza Gilani, widely seen as a move to fend off criticism by making good on electoral promises to devolve greater power to parliament.

"It is a signal to political parties and the army that he is willing to accept his reduced position as a figurehead," said Raees.

But this will unlikely be enough to appease his critics.

The opposition Pakistan Muslim League-N is calling on Zardari to relinquish powers he inherited from Musharraf to dissolve parliament and sack the prime minister -- the so-called 17th amendment to the constitution.

A key problem, Masood said, was that Zardari had very few allies left. "The media and military are not very supportive, which means his future is really uncertain and he will have to surrender his powers."

Tensions have simmered between the army and Zardari for months, notably over a US aid package signed into law in Washington in October.

It earned a terse rebuke from army chief General Ashfaq Kayani, who expressed "serious concerns" about strings attached to some of the funding.

Any political fracas will likely unnerve Pakistan's Western allies, who have been pressing Islamabad to expand a multi-pronged offensive launched earlier this year against Taliban rebels across swathes of the northwest.

The offensives have sparked a wave of retaliatory suicide bombings by the Taliban, with more than 430 people killed in Pakistan in the past two months.

"Politicians are not paying attention to real issues; the war against the Taliban, suicide bombings and the economy," said Hasan Askari, a visiting professor at Johns Hopkins University.

"Pakistani politics is personalized, and only the issues which can pull down Zardari are being focussed on."