He is the third generation of his family to assume a leading role in the PPP -- the party was set up by his grandfather Zulfiqar Ali Bhutto, Pakistan's first elected prime minister.
The BBC's Shahzeb Jillani in Islamabad says that security fears faced by the MQM and other relatively liberal parties including President Zardari's Pakistan People's Party (PPP) and the Awami National Party (ANP) are overshadowing the run-up to the vote.
Defence and political analyst Hasan Askari Rizvi says that while the PML-N may improve its standing comparative to the PPP, neither group is likely to win a straight majority out of the 275 seats up for grabs.