Bilawal, recently named patron-in-chief of the Pakistan People's Party, developed differences with Zardari and his sister, Faryal Talpur, over the party's handling of key issues, including militant violence, sectarian attacks against Shias and the award of party tickets for the polls scheduled for May 11.
Two sources privy to the development told PTI that Bilawal had made it clear to his father that he felt the PPP had not strongly taken up issues like the shooting of teenage rights activist Malala Yusufzai by Taliban fighters last year and three devastating bomb attacks on Shias in Quetta and Karachi that killed nearly 250 people.
Bilawal was also upset with the PPP's handling of issues that affect the youth, especially in the wake of efforts by other parties like Imran Khan's Pakistan Tehrik-e-Insaf to woo the youth ahead of the polls, the sources said.
The 24-year-old nominal chief of the PPP was angered by Faryal Talpur's refusal to award tickets to certain candidates in Sindh province that he had recommended, a source said.
"Last month, Bilawal had recommended the names of some 200 PPP workers and asked former Sindh Chief Minister Qaim Ali Shah to give them jobs but Talpur had intervened, causing bad blood between them," the source said.
Bilawal discussed these matters with his father and sought authority to take decisions in party matters. But Zardari sided with his sister, who plays a key role in the PPP's affairs, the source said.
"When Zardari told him that he would be handed over the command of the party after he is groomed politically, Bilawal got upset and left for Dubai," a source said.
Matters got so heated on one occasion that a source quoted Bilawal as saying: "If I had to vote, even I wouldn t vote for the PPP."
Bilawal's abrupt departure for Dubai last week has caused considerable disquiet within the PPP as the party had been banking on him to appeal to the voters who have traditionally voted for the Bhutto family.
"Bilawal had been projected as the PPP's star campaigner as the President cannot participate in the campaign due to pressure from the courts," a PPP leader said. "Without Bilawal, the PPP cannot touch the emotions of the people, especially the hard core PPP workers," said the PPP leader, who did not wish to be named.
The leader said he feared the PPP might not be able to get the "Bhutto vote" if Bilawal did not take part in the campaign.
PPP leaders have acknowledged that Bilawal will not be present when the party launches its election campaign on April 4 from Garhi Khuda Buksh, the traditional stronghold of the Bhutto family in Sindh.
However, they contended that Bilawal was not participating in the event for "security reasons" and would instead deliver a telephonic address.
Latif Khosa, recently elected secretary general of the PPP, told PTI that there were security threats to the party's leadership, especially Bilawal. He said: "Bilawal may not attend election rallies due to security concerns and is likely to address gatherings on telephone or via video-conferencing."
PPP spokesman Qamar Zaman Kaira too said Bilawal would not attend the rally on April 4 because he was "facing more threats than other leaders of the PPP". Party leaders are also concerned that the PPP's campaign is now likely to be led by former premier Yousuf Raza Gilani, who is known for his lack of charisma.
This would place the PPP at a disadvantage as it is up against seasoned campaigners like Imran Khan and PML-N chief Nawaz Sharif.
Gilani sought to play down the issue of Bilawal's sudden departure from Pakistan, saying there were no differences between Bilawal and Zardari or Talpur. "In our families, our children give immense respect to their elders," Gilani told PTI.
Hasham Riaz, Bilawal's chief of staff, said Bilawal had gone to Dubai for "routine business". He claimed the reports of differences between Bilawal and his father "mere rumours".
Asked if Bilawal would come back to Pakistan, Riaz said: "Of course." Bilawal himself will not be eligible to contest polls till he turns 25 in September.
The PPP had formally launched his political career at a massive rally in Garhi Khuda Baksh that marked the death anniversary of his mother, former premier Benazir Bhutto, in December last year