One of Tunisia’s most popular parties has pulled out of talks over the date of the country’s first election since the fall of Zein al-Abidine Ben Ali earlier this year, potentially throwing the country’s political transition into disarray.

The Nahda party, Tunisia’s main Islamist party, has withdrawn from a representative council set up to safeguard the goals of the revolution after the previous regime’s parliament was dissolved. It says it will not return until there is clear agreement on the date for an election.

Nahda and other leading parties want the election to be held on July 24, but a newly created electoral commission wants the election to be held in October, allowing it more time to prepare for polls. Noureddine Behiri, a member of Nahda’s executive bureau, announced late on Monday that the party was “suspending” its participation in the Higher Council for the Achievement of the Goals of the Revolution until a clear election date had been agreed on. Local media reported on Tuesday that compromise dates of September had been suggested.

The political crisis comes as sit-ins for improved services and jobs, and spontaneous strikes at companies large and small, show little sign of abating. Rumours of a strike by petrol-tanker drivers led to queues at petrol stations on Monday, while a strike by customs officials demanding the departure of a senior manager caused further problems for exporters.

A loan package of $20bn (£12bn) was pledged by the G8 for Egypt and Tunisia. This money is to help Tunisia cover a budget deficit that is set to widen significantly: the interim government has already announced several state-funded projects aimed at generating jobs, as well as fiscal incentives to encourage private-sector investment in the medium term.

The transitional cabinet, appointed under Beji Qaid Sebsi as prime minister, wants elections to be held on 24 July. Parties including Nahda and the Progressive Democratic Party have also argued against any postponement.

However the electoral commission wants to postpone until October 16 the nationwide vote for a constituent assembly that will serve as a parliament and also write a new constitution. This allows it more time to draw up a new register of voters and train new electoral officials.

The communist PCOT and some smaller leftist allies say that hasty election preparations could favour elements of the old regime. “The situation is really very critical,” said Moncef Marzouki, leader of the centrist Congress for the Republic party, which opposes any postponement. “The public is fast losing confidence in the parties and people are taking things into their own hands, after what has been a true popular revolution. Our party is not really ready for this election, but only an election can produce a government seen to have legitimacy.”