"Musharraf is running out of time," Foreign Minister Shah Mahmood Qureshi told reporters. "If he fails to decide to quit within the next two days, the impeachment process will take its course."
Qureshi is a member of the Pakistan People's Party, the dominant group in the ruling coalition which announced its intentions last week to impeach Musharraf.
The building momentum to throw the president out of office has injected even more uncertainty into an already volatile situation in Pakistan, a country whose stability the U.S. considers critical to success in the war on terror.
Musharraf dominated Pakistan for years after seizing power in a 1999 military coup, making the country a key strategic ally of the U.S. by supporting its fight against the Taliban and al-Qaida. But his popularity at home has been dwindling.
Many Pakistanis blame rising violence in their country on his alliance with the United States. Musharraf's popularity sunk to new lows in 2007 when he ousted judges and imposed emergency rule. Then his rivals came to power after February parliamentary elections, largely sidelining him.
The United States has said publicly the impeachment debate is an internal matter and Pakistan's army, which Musharraf formerly headed, has also remained neutral.
There is no precedent for impeaching a president in Pakistan's turbulent 61-year history.
Under the constitution, a president can be impeached for violating the constitution or "gross misconduct." Coalition officials have said Musharraf's removal of judges and imposition of emergency rule last year could be cause for impeachment.
Coalition officials said Saturday they have completed a draft of the impeachment charges but it still needs approval from the party leaders.
On Friday, allies and rivals of the president confirmed back-channel talks are under way to avoid an impeachment process that could further destabilize Pakistan.
Musharraf's supporters want protections for him if he steps down, while suggesting they could use the courts to challenge an impeachment.
Tariq Azim, a senior member of the main pro-Musharraf party, insisted Saturday the president won't quit.
"President Musharraf is confident about defending himself in the parliament and defeating the charge sheet easily because whatever he did, he did in the interest of the country and for the nation," Azim said.
On Friday, Mushahid Hussain, another Musharraf ally, said the president may turn to the courts to forestall an impeachment.
But Raza Rabbani, a member of the Pakistan People's Party, warned Musharraf this matter will not be decided in the courts.
"The venue cannot be changed," Rabbani said. "This should be clear to everyone as impeachment is a constitutional affair, and that could only be done through the parliament."
Whether Musharraf decides to quit could depend on what his rivals are willing to offer - particularly whether they will give him immunity from prosecution and let him stay in the country.
But the ruling coalition appears divided on those questions.
Sadiqul Farooq, a spokesman for the party of ex-Prime Minister Nawaz Sharif - whom Musharraf ousted in the 1999 coup - insisted immunity was out of the question.
Sharif's party is the second-largest in the coalition, and it has said Musharraf should be tried for treason, which carries a maximum punishment of death.
The PPP has taken a softer tone.
Information Minister Sherry Rehman said Saturday that the party "never indulges in the politics of revenge as it wants a stable Pakistan and a sustainable democracy in the country."
If Musharraf quits, whether he could safely stay in Pakistan is an open question. He is despised by Islamist militants and has already been the target of multiple assassination attempts.
Azim, however, said no matter what, Musharraf wants to stay in Pakistan.