Pakistani opposition parties have united to lodge a no-confidence motion against Shaukat Aziz, the prime minister, accusing him of neglecting the poor and corruption.
The motion, which is due to be debated within the next week, is not expected to succeed as pro-government members hold a majority in parliament.
But it could prove an embarrassment for Aziz, a former banker and finance minister picked to head the government in 2004 by Pervez Musharraf, the president.
Analysts say it could also give heart to those opposed to Musharraf in the run-up to a general election next year.
Musharraf is also the army chief and seized power in a bloodless military coup in 1999.
Conservative religious parties and liberal supporters of former prime ministers Benazir Bhutto and Nawaz Sharif joined forces to submit the motion.
'Oust the military'
Liaqat Baluch, a deputy leader of a six-party alliance of religious parties, said on Tuesday: "All opposition parties are united on a one-point agenda, to restore democracy and oust the military from politics."
The opposition presented the National Assembly with a 500-page dossier it said contained evidence of the government's wrongdoing.
"All opposition parties are united on a one-point agenda, to restore democracy and oust the military from politics"
deputy leader of a six-party alliance of religious parties
Aziz, a former Citibank executive, has been credited with pushing through economic reforms that have turned the economy around.
Gross domestic product growth was 8.4% last year and is expected to come in at 6.6% this year.
But poverty is still widespread and many Pakistanis complain about rising prices and unemployment.
Among its accusations, the opposition says Aziz has mismanaged the privatisation of Pakistan Steel Mills, the country's biggest steel producer, after the Supreme Court blocked its sale in June on fears it was being sold cheaply.
The government has rejected the corruption accusations and demands for Aziz's resignation.
Poverty and unemployment is
widespread in Pakistan
But analysts said the motion could hurt the government and Musharraf, who has faced calls from the opposition to give up his role as army chief before.
Syed Naveed Qamar, a member of Bhutto's Pakistan People's Party (PPP), said: "All allegations of corruption against the government ultimately lead to the man wielding the real power. The buck stops with Musharraf."
Ayaz Amir, a newspaper columnist, said opposition unity was significant even if the no-confidence motion fails.
"This will be a signal that in the run-up to the next election opposition unity will be maintained and the government will face a tough time attaining its objectives."
Under the constitution, the president is elected by parliament.
Musharraf, whose term expires in November next year, has already said he can be re-elected for a second term by this assembly, before its dissolution and fresh elections.
Nasrullah Dareshak, chief whip of ruling Pakistan Muslim League (Q), said the government had the support of about 200 members in the 342-seat assembly.