Prime Minister Yousuf Raza Gilani, who has led Pakistan's coalition government since March 2008, is a consensus politician with a reputation for loyalty who commands respect across the political divide.
On Monday, he will assume executive powers with President Asif Ali Zardari signing into law sweeping constitutional reforms that strip the head of state of the power to dissolve parliament and sack the prime minister.
A former cabinet minister and parliamentary speaker who once spent five years in jail, Gilani joined the Pakistan People's Party in 1988 under the late prime minister Benazir Bhutto and has spent a lifetime in politics.
But it was only after the PPP won elections for a third time in 2008, following its leader's assassination in late 2007, that Gilani unexpectedly won a race to fill the power vacuum left by the charismatic Bhutto.
Out-ranked by Zardari, Bhutto's widower and co-chairman of the party, Gilani showed his mettle in March 2009 when he was credited with averting a major crisis by mediating between the presidency and the opposition.
Mass rallies organised by lawyers and whipped up by opposition leader Nawaz Sharif threatened to march on the capital to demand that Zardari make good on pledges to reinstate the independent judiciary sacked by the former leader, General Pervez Musharraf.
Following consultations with the military, presidency and the opposition, Gilani went on television to promise the judges would be reinstated, averting the possibility of escalating chaos in the unstable country.
Since then, he has been considered close to Pakistan's powerful military and a prominent advocate of major offensives against homegrown Taliban in the northwest district of Swat and the tribal belt, which have won US praise. The father of five has also shored up relations with arch-rival India.
But rising food prices and an energy crisis have dented the PPP's ratings, leaving commentators divided on whether the government can ride out the dissent to become Pakistan's first government to see out a full five-year term.
Born on June 9, 1952 in Karachi, Gilani is the son of an influential landowning family from Multan, in Pakistan's political heartland of Punjab. He was educated at elite Christian-run schools.
His family has a long heritage as guardians of Islamic shrines and his father was an MP, but in Pakistan's feudal hierarchy they lacked the trappings of wealth and power enjoyed by the Bhuttos and other top PPP clans.
Gilani graduated from Lahore's prestigious Government College and got a masters degree in journalism from Punjab University.
He joined the Pakistan Muslim League in 1978 and served as minister for housing and works under military dictator Zia ul-Haq, who oversaw a process of Islamisation in Pakistan after having Bhutto's father hanged in 1979.
In 1988, Gilani joined the PPP, which won parliamentary elections after Zia died in a mysterious plane crash and returned Pakistan to civilian rule.
Now aged 57, he rose to power in the PPP due to his reputation as a staunch Bhutto loyalist. She appointed him as a minister in her first government from 1988 to 1990. In her second government, he was speaker from 1993 until 1997.
But after Musharraf grabbed power in a bloodless coup in 1999, Gilani was targeted in what his party called a politically motivated crackdown.
He was charged with illegally granting 350 government jobs to people and for excessive use of telephones and cars as speaker, and jailed for five years.
Later, all charges against holders of public office dating back to that time were expunged under an amnesty deal that allowed Bhutto to return from self-imposed exile in 2007.