Pakistan's president relinquished command of its nuclear arsenal to the prime minister, a political ally, and signaled he was ready to shed more power as he faces growing pressure to resign. The move came as an amnesty protecting President Asif Ali Zardari and thousands of others from graft charges expired Saturday, risking political turmoil that could distract the US-allied nation from its fight against the Taliban and other militants near the Afghan border. The political opposition called on Zardari to step down. He enjoys general immunity from prosecution as president, but the Supreme Court could choose to challenge his eligibility for the post since the amnesty decree by ex-military leader Gen. Pervez Musharraf was never passed into law. Zardari, 54, is languishing in opinion polls. He has long been haunted by corruption allegations dating back to the governments of his late wife, Benazir Bhutto. He denies the accusations that he took kickbacks that saddled him with the nickname, "Mr. 10 Percent." He also has found himself locked in a power struggle with the military, which has objected to his overtures toward rival nuclear neighbor India and acceptance of a multibillion dollar US aid bill that came with conditions some fear impose controls over the army. Zardari's office said the decision to transfer control of the National Command Authority to Prime Minister Yousuf Raza Gilani was a step toward ceding sweeping presidential powers that had been adopted by Zardari's predecessor, Musharraf. The authority comprises a group of top military and political leaders who would make any decision to deploy nuclear weapons. Gilani is a veteran lawmaker and member of Zardari's own party. He spent five years in prison under Musharraf's regime, accused of cronyism and abusing his authority when serving as Parliament speaker, despite a reputation for evenhandedness in his treatment of opposing lawmakers. A higher court eventually overturned his conviction. "He (Zardari) has taken the correct and democratic step and we will see many more steps taken by the president along these lines to empower the prime minister and to empower the Parliament," spokeswoman Farahnaz Ispahani said. "He is giving up the dictatorial powers that Gen. Musharraf - as an unelected leader - needed to keep himself in power." Zardari also reissued 27 other Musharraf-era ordinances concerning the competition commission, defense housing and other matters ahead of a midnight Saturday deadline set by the Supreme Court. In an interview Friday with Express News TV, Zardari said he was also likely to give away authority he inherited from Musharraf to dissolve Parliament and appoint services chiefs by the end of this year, as the opposition has long demanded. Doing that would weaken him politically and reduce the president to a more ceremonial role, but could reduce some of the pressures on him to step down. A spokesman for the opposition party headed by former Prime Minister Nawaz Sharif called on Zardari to resign despite his immunity. "Asif Ali Zardari should take the high moral ground and resign so that his credibility will increase," said Sadiqul Farooq, spokesman for the Pakistan Muslim League-N. Analysts said the transfer of authority signaled Zardari's willingness to divest powers as part of a compromise that would enable him to keep his job. "It appears to be a self-defense and survival strategy," said Rasool Bakhsh Rais, a political science professor at Lahore University of Management Science. A military coup to oust Zardari appears unlikely, as does impeachment, since he heads the largest party in Parliament. But the amnesty's expiration and his dispute with the powerful military leave him vulnerable as he struggles to maintain his hold on the presidency at a time when Pakistan's foreign allies would prefer political stability. Pakistan is embroiled in a bloody war against Islamist militants and has endured dozens of bombings this year that have left hundreds dead. Interior Minister Rehman Malik said Saturday that 73 suspected militants, including 11 would-be suicide bombers and one suspected in the beheading of a Polish engineer, had been arrested in recent weeks. He alleged some of those interrogated had confessed to planning attacks on the presidency, Parliament and the prime minister's house.