The 24-year-old Bilawal had left for Dubai over a week ago after a tiff with his father over the affairs of the PPP.
A source in the PPP told PTI that Zardari had gone to Dubai on a "private visit" and the main purpose of his trip was to placate Bilawal. "The PPP cannot afford to go into the May 11 polls without Bilawal. Many in the PPP believe that the son of the late Benazir Bhutto alone can mobilise voters in favour of the party," the source said.
However, presidential spokesman Farhatullah Babar told PTI that Zardari's visit had nothing to do with reports of differences with Bilawal. "President Zardari has gone to the United Arab Emirates on a private visit. And I don't know whether Bilawal is in London or somewhere else," Babar said. He contended that reports about a rift between Zardari and Bilawal were "baseless".
Bilawal, recently named patron-in-chief of the PPP, 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.
The PPP had earlier announced that Bilawal would lead the party's election campaign. Following his abrupt departure for Dubai, PPP leaders said Bilawal had left the country due to security concerns. They further said Bilawal would participate in the campaign but would not lead it.
The source in the PPP said, "At this critical juncture when there are rifts among party leaders over the award of tickets, President Zardari cannot afford to leave the country. But Bilawal's issue is bigger than others, and he had to go to Dubai to convince Bilawal that the PPP may not be able to effectively appeal to voters without him."
Bilawal will not be able to contest polls himself till he turns 25 in September.
The PPP had formally launched Bilawal's political career at a rally marking Benazir Bhutto's death anniversary in December last year.
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