Sources told the TV channel that the decision was taken at a meeting of senior leaders of the PPP held late Tuesday under the chairmanship of President Asif Ali Zardari.
The meeting also decided that a session of the National Assembly would be summoned Thursday for electing the leader of the house.
However, former prime minister Yousuf Raza Gilani expressed reservations over the name of Shahbuddin during the meeting of coalition partners, who entrusted Zardari to nominate the new prime minister.
The Supreme Court Tuesday ruled that Gilani stood disqualified as prime minister as well as MP since the apex court's April 26 verdict holding him in contempt of court for refusing to write to the Swiss authorities to reopen corruption cases against Zardari.
A three-member bench led by Chief Justice Iftikhar Mohammad Chaudhry heard a set of constitutional petitions challenging National Assembly Speaker Fehmida Mirza's ruling over Gilani's qualification as prime minister.
A seven-member bench of the apex court had convicted Gilani April 26 of contempt of court. The court, however, sentenced him only "until the rising of the court", or till the time the judges left the court chamber. That was only for about 30 seconds after the verdict was handed down.