millions, Zardari is barred from campaigning as head of state, but his Pakistan People's Party (PPP) has been rudderless ahead of Saturday's vote.
Pakistan President Asif Ali Zardari paying obeisance at the shrine of Khwaja Moinuddin Chishti in Ajmer. PTI
Zardari's government is the first in Pakistan to complete a full five-year term and hand over to another democratically elected administration, yet no PPP leader has led the party's campaign for re-election.
The major rallies once addressed by his late wife, Benazir Bhutto, and her father Zulfiqar Ali Bhutto, were cancelled in the face of Taliban threats. His son and the PPP chairman, Bilawal, speaks in TV adverts but has gone to ground.
Helped by the army chief of staff's determination to keep to the sidelines and the opposition's unwillingness to force early elections, analysts credit Zardari's wheeler-dealer abilities for keeping him in power.
The 57-year-old survived enormous pressure from a judiciary determined to put him on trial for corruption, sacrificing his first prime minister, but otherwise has emerged relatively unscathed.
An ice cream vendor passes by a banner featuring portraits of Pakistan's President Asif Ali Zardari and Bhutto's family members along a street in Islamabad. AFP photo/Aamir Qureshi
Born on July 26, 1955 into a land-owning, polo-playing family from southern province Sindh, Zardari was educated in Pakistan and went on to study business in London, although he never graduated from university.
Barely known at the time of his arranged marriage to Bhutto in 1987, he carved out a powerful position for himself, serving as a government minister during his wife's two short-lived premierships.
After her first administration, he was jailed in 1990 for three years and was back behind bars within half an hour of her second government's dismissal in 1996, held for eight years for alleged corruption, murder and drug smuggling.
He has always claimed the allegations were politically motivated and he has never been formally charged or put on trial.
When his wife returned home to contest elections in October 2007, Zardari stayed behind in Dubai with their three children.
Bombers targeted her homecoming, killing 140 people. Benazir survived, but two months later she died in an attack on a political rally in Rawalpindi. Zardari, in Dubai, reportedly learned of her death from television news.
Her assassination stunned the world, plunged Pakistan into mourning and propelled Zardari out of the shadows and into the political limelight.
Kept at bay for years by the PPP, which was uncomfortable with his shady reputation, Zardari took control as co-chairman alongside his then teenage son, who is still too young to seek election.
The PPP won 2008 elections on a wave of sympathy and unanimously supported Zardari's candidacy for the president and he assumed office, replacing general Pervez Musharraf when he was threatened with impeachment.
In 2010, Zardari earned some praise for relinquishing much of his power to the prime minister, rolling back on decades of meddling by military rulers in an effort to institutionalise parliamentary democracy.
In this file photograph Pakistan's President Asif Ali Zardari (L) waves with his son and chairman of ruling Pakistan People's Party (PPP) Bilawal Bhutto (R) to supporters outside the Bhutto family mausoleum in Garhi Khuda Bakhsh, on the fifth anniversary of the assassination of Benazir Bhutto. AFP photo/Rizwan Tabassum
But whether reforms that his government introduced can get the PPP re-elected remains doubtful and his record in government has been weak.
The administration has been pilloried for being ineffectual, presiding over a deteriorating economy and being unable to stem Taliban attacks. He has suffered abysmal personal approval ratings and is almost never seen in public.
Relations between the United States have been deeply troubled. In a country where the military still has a tight hold on foreign policy, Zardari is a close but often considered an ineffectual US ally.
His future role will depend on the PPP's showing at the polls. Bilawal is now sole chairman of the party and will in September be old enough to run for parliament. Many expect Zardari to beat a hasty retreat back to Dubai or slip back again into the shadows.