Leaders of Pakistan's ruling coalition are due to meet in London this week to resolve differences over how to reinstate judges dismissed in November by President Pervez Musharraf, officials said on Thursday.
Strains over the issue within the month-old coalition, led by the party of assassinated former prime minister Benazir Bhutto, have raised speculation that the anti-Musharraf alliance could collapse, though party leaders have asserted their unity.
Western allies in the war on terrorism dread nuclear-armed Pakistan sliding into a prolonged period of instability.
Critics fear the failure to move forward over the judges has diverted Prime Minister Yousaf Raza Gilani's government from more pressing issues like rising inflation, deteriorating trade and fiscal deficits and the fight against Islamist militancy.
Asif Ali Zardari, Bhutto's widower who succeeded her as leader of the Pakistan People's Party (PPP), was due to fly to London on Thursday to meet Nawaz Sharif, the leader of the second largest party in the coalition, after their aides failed to bridge differences over how to restore the judges.
Former prime minister Sharif, leader of the Pakistan Muslim League (Nawaz) is in London, where his wife is receiving medical treatment.
"I was leaving for Pakistan but Mr Zardari asked me to stay back for a meeting," Sharif told private Geo television.
The two, neither of whom are members of the government or parliament, met in Dubai last week for urgent consultations to break the log jam over the judges.
A panel of politicians and legal experts set up by Zardari and Sharif late on Wednesday finalised a draft of a resolution to be put before the National Assembly for the judges' restoration.
Reviving challenges to Musharraf possible
President Musharraf dismissed around 60 judges after imposing a six-week emergency rule in November last year. Musharraf purged the judiciary before the Supreme Court could deliver a verdict over whether his re-election in October while still army chief and by the outgoing parliament was lawful.
A general election in February swept away Musharraf's parliamentary support, and the restored judges could conceivably revive the case against the president's re-election.
Law Minister Farooq Naek, who was leading the panel, said there was no "deadlock" over bringing back the judges, but said legal experts differed over how to proceed.
"We have decided to refer the matter to our leaders. They will take final decision," he told reporters after a four-hour meeting of the panel.
Zardari and Sharif agreed in Dubai to restore the deposed judges on May 12 through a parliamentary resolution, after the coalition missed a previous self-imposed deadline of April 30.
Sharif, the prime minister overthrown by Musharraf as army chief in 1999 coup, wants the judges restored immediately and the president to be impeached, but Zardari wants to avoid immediate confrontation Musharraf.
Zardari's PPP favours linking reinstatement of the judges to a constitutional package that would also curb the president's powers by removing his right to dismiss a government.
Zardari is reluctant to reinstate some judges, notably Chief Justice of Supreme Court Iftikhar Chaudhry, who became a cause celebre after he defied pressure from Musharraf to resign in March last year.
Analysts say Zardari has several reservations about Chaudhry, and the PPP would prefer to restore him and then pack him off to retirement by amending clauses in the constitution governing the appointment of senior judges.
Last October, Chaudhry accepted challenges to an amnesty Musharraf granted Bhutto and Zardari, along with several other politicians, to allow them to return to Pakistan without fear of being prosecuted in old graft cases they say were politically motivated.