Faced with a non-bailable arrest warrant against Makhdoom Shahabuddin, its first choice for prime minister's post, ruling Pakistan Peoples Party on Thursday fielded senior leader Qamar Zaman Kaira at the last minute besides a "covering" candidate.
President Asif Ali Zardari, the chief of the PPP, had earlier nominated Shahabuddin for the post of premier.
Senior PPP leader Raja Parvez Ashraf, was named as a "covering" or alternative candidate in case Shahabuddin's nomination papers were rejected for some reason.
As Shahabuddin was filing his nomination papers at the National Assembly, a special court of the Anti-Narcotics Force in Rawalpindi issued a non-bailable arrest warrant against him in connection with alleged irregularities in the import of a large quantity of the controlled drug Ephedrine during his tenure as health minister.
Though it was not immediately clear whether the warrant would affect Shahabuddin's candidature, the PPP decided to take no chances and senior leader Kaira too filled nomination papers for the election of the premier.
Kaira's papers were submitted shortly before the national assembly secretariat stopped accepting nominations at 2 pm.
All three PPP candidates Shahabuddin, Ashraf and Kaira served as ministers in former premier Yousuf Raza Gilani's cabinet.
Shahabuddin and Ashraf have been linked to graft cases that are currently being examined by the Supreme Court while there are no allegations against Kaira.
Arrest warrant was also issued against Gilani's son Ali Musa.
The Supreme Court is examining allegations about out-of-turn quotas for importing Ephedrine granted during Shahabuddin's tenure as health minister while Ashraf, who served as power minister, has been linked to a scam involving private power projects.