Members of the president's party in Tunisia will quit the coalition government, the state-run news agency TAP reported Sunday.
The move threatens to worsen a political crisis, set off after an opposition leader was assassinated there last week.
The Congress for the Republic Party, which counts Tunisian President Moncef Marzouki among its ranks, has three ministers and two secretaries of state in the government, TAP reported.
The five officials will "continue to shoulder their responsibilities within their respective departments to avoid any administrative vacuum," TAP said, citing Chokri Yacoub, a party leader.
The news comes one day after Prime Minister Hamadi Jebali said he would step down if a caretaker government he is forming fails to win approval from Tunisia's National Constituent Assembly.
In response to the shooting death of Chokri Belaid, Jebali sacked his government and said he would appoint a new one to serve until the next election.
However, a top official of Jebali's own Ennahda party labeled Jebali's moves "non-binding," raising questions about his leadership.
Belaid, a prominent secular politician who decried violence, was shot dead as he left his home Wednesday morning for work. No one has claimed responsibility for the attack, but Belaid's widow and others blamed the climate fostered by Jebali's Ennahda party.
Jebali denied that Ennahda had anything do with Belaid's killing and said he hoped to get approval for his new government from his party and others.
"The government, I feel, is backed by a lot of people, mainly among ordinary people. I hope that political parties will translate the view of our people," Jebali said Friday.
As he spoke, thousands of Tunisians demonstrated in the streets of the capital in outrage over the assassination, calling on Jebali to resign.
The killing of Belaid was the country's first high-profile political assassination since Tunisia's "Jasmine Revolution" that toppled President Zine el Abidine Ben Ali two years ago and spawned the Arab Spring.