With a self-imposed deadline looming, Pakistani leaders had yet to clinch a deal Sunday on restoring judges sacked by President Pervez Musharraf, an issue that has threatened to break up the ruling coalition.

U.S.-backed Musharraf removed dozens of judges and declared emergency rule in November to halt legal challenges to his presidency.

Anti-Musharraf parties won February parliamentary elections, putting together a coalition government that has promised to reinstate the judges _ a move that could increase pressure on Musharraf to resign if the courts revisit his eligibility for office.

But ruling coalition officials have failed to agree on the mechanics of the reinstatement, raising the prospect of an end to their partnership after just six weeks.

After missing an April 30 deadline to resolve the issue, coalition leaders said they were aiming to introduce a parliamentary resolution on the matter by Monday. Asif Ali Zardari and Nawaz Sharif, the leaders of the two main coalition parties, met Friday in London. Negotiators from the parties also met Saturday, but no agreement had come by Sunday morning.

Sharif, a former prime minister ousted by Musharraf in a 1999 coup, has demanded outright restoration of the deposed judges. But Zardari has linked their reinstatement to broader judicial reforms.

Complex legal and political issues, including the status of the judges Musharraf installed after the purge, have proved stumbling blocks to a deal.

Farhatullah Babar, of Zardari’s party, said meetings late Saturday and early Sunday in London made some progress.

“We believe that differences have been narrowed and hope to achieve a consensus soon,” he said, insisting, “There is no impasse.”

But Sadiqul Farooq, a spokesman for Sharif’s party, said the negotiations have made “no tangible achievement on the question of restoring the judges.”

“We cannot reject the impression that the coalition has reached a make or break point,” Farooq said.

He said if the deadline is not met, party leaders will meet Monday to consider their future in the coalition, including whether to quit the Cabinet or even shift to the opposition.

Sharif’s party has argued that the government could issue a simple order to bring back the judges after the parliamentary resolution.

A senior party colleague of Zardari reacted sharply Saturday to Sharif’s suggestion that police could escort the justices back to their jobs.

“If police restore the judges ... then there will be a political and constitutional crisis,” Information Minister Sherry Rehman said. “We need to be responsible and avoid unnecessary confrontation at a time when Pakistan is beset with so much conflicts and economic and social pressures.”

Rehman was referring to concern that Musharraf and his allies could seek to block the return of Iftikhar Mohammed Chaudhry as chief justice.

Musharraf has accused Chaudhry of corruption and conspiring against his plan to guide Pakistan back to democracy after eight years of his military rule.

Zardari insists judges sworn into the Supreme Court after the purge be retained so they do not oppose the new government in a legal tussle that would cast the country into political turmoil.