The Tunisian General Labour Union (UGTT) called for a referendum on the political system and the amendment of the electoral law on Thursday.
The UGTT rejected the proposed amendment to the electoral law, which includes raising the electoral threshold (the percentage of votes required to obtain a seat in parliament to five per cent).
The proposed amendments include additional proposals on political funds, campaign financing, political party financing and several other points.
The UGTT's demands come in the midst of an acute political crisis that Tunisia is undergoing, following Elyas Fakhfakh's dismissal of Ennahda ministers.
The UGTT's Spokesperson Sami Taheri announced: "The union is not concerned with any consultations to form a new government as long as the current government is in place," according to Agence Tunis Afrique Presse.
Taheri added: "The current situation requires the Ennahda movement and its allies to resort to the law if they want to topple the government."
Ennahda's Shura Council announced that the Head of the movement Rached Ghannouchi was tasked with holding consultations with the president of the republic, parties and national organisations to form a new government.
Last Wednesday, a censure list calling for the withdrawal of confidence from Fakhfakh's government was presented to parliament. The petition was signed by 105 deputies, including MPs from the Ennahda party, Heart of Tunisia (27 seats) and Al-Karama Coalition (19 seats).