Islamabad ? 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 U.S.-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.