Prime Minister Hamadi Jebali held last-ditch talks on Friday with a raft of party leaders as he hammered out a technocrat government designed to pull Tunisia out of its worst political crisis since the revolution.
Jebali has promised to announce the new government line-up on Saturday, and says he will resign if it is rejected by the National Constituent Assembly which is dominated by his own Islamist party Ennahda.
The embattled premier met the heads of all the parties in Tunisia's ruling coalition, namely Ennahda's Rached Ghannouchi, Ettakatol's Mustapha Ben Jaafar and Mohamed Abbou of President Moncef Marzouki's Congress for the Republic.
The meeting took place behind closed doors at a palace in the Tunis suburb of Carthage, which was surrounded by heavy security.
Jebali's plan, first announced in the wake of public outrage at the killing of leftist leader Chokri Belaid, is broadly supported by secular opposition parties, trade unions and civil society groups, for whom it is the only way of out of the unfolding crisis.
But it has met resistance from Jebali's ruling Islamist party, in which he is considered a moderate, and which is planning demonstrations on Saturday to protest against the initiative.
The Islamists have joined ranks with Marzouki's centre-left party and two other parties, in proposing that the new cabinet comprise both politicians and independents.
The crisis in Tunisia, which has for months been rocked by social unrest including protests that often degenerate into violence, has sown fear and uncertainty in the first country to undergo regime change caused by Arab Spring protests.
Poverty and unemployment, two key factors that led to the revolution that ousted Zine El Abidine Ben Ali in 2011, continue to grip Tunisia.
Belaid's killing has enflamed tensions between liberals and Islamists over the direction of the once proudly secular Muslim nation, with opposition protesters engaging in street clashes with police.
As well as the pro-Ennahda rally, Saturday will see two memorial ceremonies for Belaid, one in southern Tunis and another in Jendouba in the northwest, from where his family originates.
Belaid's wife Besma Khalfaoui, who has become a symbol of Tunisia's secular opposition and scourge of the ruling Islamists since her husband was gunned down outside their Tunis home last week, is expected to attend the Jendouba ceremony.
Speaking to reporters earlier in the week, Jebali said he would announce the new government line-up on Saturday, "and if it is rejected I will submit my resignation to the president."
The premier has insisted that ministers in the new cabinet should be independent and firmly committed to not running in the next elections.
"This is the proposal I am making for the country, and the parties will be held responsible for its success or failure."
Media on Friday said Tunisia was at a "turning point."
As well as the row over the new government, there is deadlock over the drafting of the constitution, 15 months after the election of the assembly, and the country has been further destabilised by attacks blamed on radical Salafists.
"Our hope is that the voice of reason and consensus will emerge triumphant," said the La Presse.
Most of the secular parties backing the initiative are in the ranks of the opposition, but Ettakatol, a secular ally of Ennahda headed by parliamentary speaker Ben Jaafar, has also thrown its weight behind Jebali.
So too have the powerful General Union of Tunisian Workers and the UTICA union of employers.
But hardliners of Ennahda -- which controls 89 of the 217 seats in parliament after an October 2011 election -- refuse to give up key portfolios.
Sahbi Atig, the Islamist party's parliamentary leader, said "two catastrophes" took place on February 6 -- Belaid's murder and Jebali's initiative.
One of Ennahda's vice presidents, Mohamed Akrout, urged party backers to join the public rally in Tunis on Saturday in support of the Islamists, saying they "must defend their revolution."