Analysts say Musharraf's best way out would seem to be a dignified exit
Pakistan's foreign minister has said President Pervez Musharraf must stand down in the next two days or face impeachment proceedings.
"Musharraf is running out of time", said Shah Mahmood Qureshi, of the Pakistan People's Party (PPP) - a major partner in the governing coalition.
Draft charges against the president include violation of the constitution and gross misconduct, officials said.
Mr Musharraf's office has said he will not resign and will defend himself.
The impeachment campaign was launched last week by leaders of the PPP and the Pakistan Muslim League-Nawaz (PML-N), led by former prime minister Nawaz Sharif.
A PML-N official said: "There is a long list of charges against him... we will file them, by the latest, by Tuesday."
If Mr Musharraf chooses not to quit, he would be the first president in Pakistan's history to be impeached.
Weighing up options
A spokesman for the Pakistan Muslim League-Q, a pro-Musharraf party, said that the president's advisers were considering his options.
STEPS TO IMPEACHMENT
Impeachment proposers need 50% majority in Senate or National Assembly
President given notice of impeachment, and has three days to respond
Joint session of Senate and Assembly must be held between 7 and 14 days later to investigate charges
If resolution presented, joint session must approve with two-thirds majority
Nawaz Sharif, who was toppled in the 1999 coup, said he was opposed to any deal which would give his old rival a "safe passage".
He has said the president should be tried for treason, which carries the maximum sentence of the death penalty.
But the PPP, the party of assassinated former Prime Minister Benazir Bhutto, says the decision of whether to put the president on trial should be left to parliament.
Information Minister Sherry Rehman, said the PPP "never indulges in the politics of revenge as it wants a stable Pakistan and a sustainable democracy in the country".
The BBC's Mark Dummett in Islamabad says support for the president in a recent vote of confidence in the provincial assemblies has almost entirely collapsed.
Mr Musharraf's best way out would now seem to be a dignified exit before parliament meets to debate the impeachment, our correspondent says.
Talks are going on behind the scenes.
The ruling coalition parties will have to decide where the former army chief, a key ally in Washington's war on terror, is allowed to live and what protection he will receive, our correspondent says.
Mr Musharraf came to power in a bloodless coup in 1999.
He gave up control of the army last year and his allies were defeated in February's elections but he retains the power to dissolve parliament.
But his public standing suffered a huge setback in 2007 when he sacked Pakistan's chief justice and nearly 60 judges to prevent them from overturning his re-election as president.
But analysts say the president is still thought to have heavy influence over the military and its reaction will remain crucial.