Pakistan's main opposition party on Thursday called on President Asif Ali Zardari to resign after a court threw out an amnesty protecting him and senior government figures from corruption charges. The Supreme Court declared Wednesday that a 2007 National Reconciliation Ordinance (NRO) which contained the amnesty was unconstitutional and struck it down, paving the way for thousands of criminal cases to be revived. Zardari is immune from prosecution while in office, but that immunity and his eligibility for president could now be challenged, as a number of graft cases were pending against him when the NRO was passed. "We are suggesting President Zardari should resign on moral grounds. All the cabinet members must immediately tender their resignations," said Siddiqul Farooq, spokesman for the opposition Pakistan Muslim League-N (PML-N). "President Asif Ali Zardari should resign on moral grounds and should not depend upon the crutches of the constitution," he added. Pakistan's constitution guarantees Zardari immunity, but also states that presidential candidates must be pious, honest and truthful and never have been convicted in a criminal case.