Mr Zardari's 19-year-old son, Bilawal Bhutto Zardari, is expected to preside over a meeting in Islamabad later today of the dominant Pakistan People's Party central executive committee at which the decision by the party's members of the National Assembly will be formally endorsed.
The Oxford undergraduate, chairman of the party of which his father is the co-chairman and effective leader, arrived in the capital earlier this week amid speculation that he was summoned home to formally announce his father's candidacy to succeed ousted president Pervez Musharraf in the country's top job.
Mr Musharraf resigned on Monday to avoid impeachment proceedings by the coalition government, dominated by Mr Zardari's PPP and former Pakistan prime minister Nawaz Sharif's Pakistan Muslim League (N).
Some PPP leaders have expressed reservations about nominating Mr Zardari, still viewed with deep suspicion by many of Pakistan's 160 million people. Others, too, believe Mr Zardari, who is neither an MP nor a member of the Government, is better suited to his present role of running the party and dominating the cabinet through a surrogate prime minister.
Mr Zardari has long maintained that he wants to be the "Sonia Gandhi" of Pakistan, a reference to the Italian-born widow of former Indian prime minister Rajiv Gandhi who now dominates Indian politics through her presidency of that country's ruling Congress party.
Mr Zardari, 52, a former polo-playing bon vivant who now suffers from a heart condition and diabetes, was politically sidelined and living in Dubai before his wife was assassinated on December 27 last year. Since seizing control of the PPP and leading it to victory in February's election, Mr Zardari has dominated the country's affairs.
Though there had been suggestions during Mr Musharraf's tenure as president that the role should be stripped of many of its major powers, analysts in Islamabad expect that if Mr Zardari accepts the appointment he will oppose any whittling down of those powers.
At present, the president has exclusive authority to dissolve parliament and appoint such key officials as the army chief of staff as well as judges.
Mr Zardari's nomination is thought likely to further exacerbate tensions within the ruling coalition, already at breaking point over the issue of reinstating chief justice Iftikhar Chaudhry and other judges sacked by Mr Musharraf when he declared an illegal state of emergency last year. Though they present an outward appearance of bonhomie, aides say Mr Zardari and Mr Sharif are deeply suspicious of each other, and Mr Sharif is dead set against his rival becoming president.
Tensions between them are set to reach a climax later today with indications Mr Sharif's PML (N) party is poised to walk out of the coalition and move to the opposition benches.
Mr Sharif's fury with Mr Zardari over the failure to reinstate the chief justice and other judges, despite repeated promises to do so, intensified yesterday when it was disclosed that the PPP boss is now insisting on a so-called "minus one" formula for the restoration process.
Highly placed sources said Mr Zardari was insisting the volatile chief justice not be restored, pointing out that his exclusion from the Supreme Court bench was part of the internationally agreed arrangement that led to Mr Musharraf's resignation. Most analysts believe the "minus one" formula is likely to be the final straw for Mr Sharif and a red rag to the powerful lawyers' movement that has led the fight for democracy in Pakistan.
Highly placed PPP sources said last night that the party was untroubled by the prospect of Mr Sharif abandoning the coalition.
