Religious Affairs Minister Khursheed Shah, a senior leader of the Pakistan People's Party (PPP), told media the parliament session would begin Friday at 5.30 pm, while nomination papers would be submitted on Thursday, Geo News reported.
Earlier, it was reported that PPP leaders have picked Mr Shahabuddin for the office of the Prime Minister.
Sources told Geo News the decision was taken at a meeting of party leaders held late on Tuesday under the chairmanship of President Asif Ali Zardari.
However, the final choice for the post would be announced after a PPP parliamentary party meeting later Wednesday.
Mr Shahabuddin is a member of the National Assembly from Rahim Yar Khan while Mr Mukhtar represents Gujrat constituency - both in Punjab province. Mr Mukhtar was formerly the defence minister.
However, Mr Gilani expressed reservations over the choice of Mr Shahabuddin during the meeting of coalition partners, who entrusted Mr Zardari to nominate the new Prime Minister.
The name of Mr Zardari's sister Faryal Talpur was also mentioned at the PPP meeting held on Tuesday night.
Dawn News said Mr Zardari also suggested the names of young Foreign Minister Hina Rabbani Khar and Khursheed Shah for the post.
The Supreme Court on Tuesday ruled that Mr Gilani stood disqualified as Prime Minister as well as Member of Parliament since the topcourt's April 26 verdict holding him in contempt of court for refusing to write to the Swiss authorities to reopen corruption cases against President 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 that despite conviction for contempt of court Mr Gilani could continue as the Prime Minister.
A seven-member bench of the Supreme Court had convicted Mr 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.