President Pervez Musharraf has signed into effect changes to the constitution that enhance his powers.
The president has promised to step down as military head
The move paves the way for the national parliament and Pakistan's four provincial assemblies to hold a vote of confidence in his presidency.
Prime Minister Zafarullah Jamali says he is confident that President Musharraf will win the vote.
The amendments follow a deal with Pakistan's main Islamist parties which had been critics of the president.
The vote of confidence is due to be held on Thursday.
General Musharraf "will get an overwhelming majority," Prime Minister Jamali told reporters on Wednesday.
The package of constitutional changes were approved by the two houses of the national parliament this week.
The BBC's Zaffar Abbas says the changes legitimise all General Musharraf's actions since his 1999 military coup.
Analysts say they mark an end to a protracted struggle between parliament and President Musharraf over how much power he should have.
While Pakistan's main Islamist parties have now given their support to the president, the other main opposition parties have voiced their disgust at the deal.
Islamists had campaigned against Musharraf's powers
Last week, General Musharraf agreed to the Islamists' long-running demand that he step down as head of the army.
Parliament has been paralysed by protest since General Musharraf assumed wide-ranging powers in 2002.
The measures approved by parliament mean the president can dissolve parliament and dismiss the prime minister - such a move would have to be ratified by the Supreme Court.
Chief justice replaced
As part of the package of measures that took effect on Wednesday, President Musharraf has appointed a new chief justice to oversee the Supreme Court.
He has picked Nazim Hussain Siddiqui - a senior Supreme Court judge since 2000 - for the post.
In 2000, Justice Siddiqui was one of a panel of Supreme Court judges who ruled against opposition leaders when they challenged the bloodless coup that had brought General Musharraf to power.
Tariq Mahmood, the president of the Supreme Court Bar Association, told the BBC Justice Siddiqui's "integrity" was beyond dispute.
Two other Supreme Court judges have questioned Justice Siddiqui's appointment, claiming they were senior to him and ought to have been considered for the job.
Differences over US
Last Friday, General Musharraf said he would step down as head of the army by the end of 2004.
This followed long negotiations between the government, loyal to the president, and the coalition of Islamist hardliners, the MMA.
They have opposed his rule and his role as an ally in the US-led war against terror.
Under the agreement, General Musharraf will stay on as president until 2007.
Last year, President Musharraf gave himself the right to remain president and military chief until 2007 and to dismiss elected governments.
The bill giving him sweeping powers - known as the Legal Framework Order - was opposed across the political spectrum.
Protests against it united the MMA with the Alliance for the Restoration of Democracy (ARD), which includes the parties of former prime ministers Nawaz Sharif and Benazir Bhutto.
Since 2002, legislators have blocked parliamentary business by banging their desks, interrupting speakers and walking out of proceedings.
The ARD remains opposed to the MMA's agreement with President Musharraf.
The aftermath of last week's attempt on General Musharraf's life
"The parliamentary system has been disfigured because of
this amendment," says Sadique al-Farooq, a spokesman for
the Pakistan Muslim League of former Prime Minister Nawaz Sharif.
"All important powers have been transferred to the
president, the prime minister will be rendered powerless
and the parliament will become a rubber-stamp."
However, information minister Sheikh Rasheed Ahmed said on Monday that the deal would bring stability to Pakistan.
President Musharraf survived his second assassination attempt in under a fortnight on Thursday, when two suicide bombers blew themselves up near his motorcade in the city of Rawalpindi.