The Pakistani parliament convenes today to pick a replacement for ousted prime minister Yusuf Raza Gilani.
But on the eve of the vote, a court has issued an arrest warrant for the candidate from the Pakistan People's Party (PPP), which has a comfortable majority in parliament along with its ruling coalition partners.
The court took the action against Makhdoom Shahabuddin over allegations he illegally imported drugs while he was health minister.
Shahabuddin has denied any wrongdoing and it is unclear whether the arrest warrant will undermine his nomination.
Gilani was ruled ineligible to hold office by the Supreme Court on June 19 over his refusal to reopen a corruption case against President Asif Ali Zardari.
Analysts say the affair highlights the power struggle between the government and activist judges.
Zardari accepted the Supreme Court decision, opting against a fight with the judiciary.
Earlier on June 21, Shahabuddin said he was honored to have been nominated.
"First, I want to thank God who has been kind to me and my country. I am very grateful to the president who has nominated me as the Pakistan People's Party candidate for the office of the prime minister of Pakistan," Shahabuddin said.
Shahabuddin is one of three candidates from the ruling PPP.
Two other candidates -- Sardar Mehtab Khan Abbasi of Pakistan Muslim League Nawaz and Maulana Fazlur-Rehman, chief of Jamiat Ulema-e Islam -- also filed their nomination papers.
Maulana Fazlur-Rehman said he was standing for the post in order to put an end to the political insecurity in the country.
"The state of affairs in the People's Party and its ongoing tussle with state institutions could lead the country to martial law. We have to save the country. We have to save democracy. For this reason, we have stepped into the arena so that we can provide a consensus candidate to the people."
Analysts say today's election in parliament is unlikely to end the political instability in Pakistan as the new prime minister will face the same order from the Supreme Court to investigate Zardari as Gilani did.
Based on reporting by AP and Reuters