Tunisia's secular opposition said this afternoon it is considering setting up an alternative "salvation government" to challenge the Islamist-led leadership.
If agreed, the move would mark a significant escalation by the country's opposition groups, who say they have no interest in reconciliation with the ruling Ennahda party.
"We will meet this evening to discuss creating a new salvation government and will study the possibility of nominating a new prime minister to replace this failed government," said Jilani Hammami, a leader of the Salvation Front coalition and Tunisian Workers' Party.
"There is no longer any doubt that the time for it to go has passed."
On Thursday, assailants shot dead opposition figure Mohamed Brahmi, the second assassination targeting the secular opposition in six months.
The opposition blames the Islamist Ennahda party for the killing and protests have erupted in the capital Tunis as well as other provincial cities.
The secular opposition had already been poised to mobilise against the Islamist-dominated government, inspired by the mass protests in Egypt that saw the army oust and detain former Islamist president Mohammed Mursi.
Critics of the Tunisian opposition say the campaign is threatening stability during a fragile transition process since the overthrow of president Zein El Abidine Ben Ali in 2011.
The speaker of parliament said yesterday the government was discussing a new power-sharing deal and urged politicians withdrawing from the transitional Constituent Assembly to reconsider.
"It's not rational to throw in the towel just metres away from the finish line," Mustafa Ben Jaafar said in a televised speech.
Ben Jaafar, a member of one of the secular partners in the Ennahda-led government, said the body was only weeks away from finishing the new constitution.
But the opposition position has hardened.
"The opposition completely rejects all efforts at reconciliation presented by the head of the Constituent Assembly in terms of expanding powers," Mr Hammami told Reuters.
By today, the number of parliamentarians who had withdrawn from the 217-member body had risen to 64.
They will join a sit-in outside the parliament.
Protests started there yesterday after Mr Brahmi's funeral and drew crowds of thousands, the largest the capital has seen in months.
Hundreds of pro-Ennahda demonstrators took part in a rival rally.
Police used teargas to disperse protests in Tunis as well as Sidi Bouzid, the birthplace of the Tunisian revolt and hometown of Mr Brahmi.
