Tunisia's ruling Islamist Ennahda party and the opposition have failed to reach an agreement on appointing a new prime minister, with both sides pledging to continue negotiations.
After an unsuccessful meeting on Saturday morning, the parties sat down behind closed doors again at around 16:30 GMT to carry on discussions.
The dialogue came to an end six hours later with no result, although senior Ennahda official Ameur Larayedh said that the two sides would continue talks on Sunday.
Tensions have gripped Tunisia since the 2011 uprising that toppled veteran dictator Zine El Abidine Ben Ali and were exacerbated with the murder this year of two opposition politicians by suspected Islamist radicals.
Ennahda, a moderate Islamist party whose resignation has been demanded by the opposition, has pledged to step down and allow the creation of a government of independents as part of a roadmap.
After months of stalling, the Islamist-led government opened talks with the opposition on October 25 to form the new government, agree on a much-delayed constitution and prepare for elections.
The roadmap to resolve the crisis was drafted by mediators including the powerful UGTT trade union.
Disagreement over frontrunners
A meeting of party leaders on Friday to chose a new prime minister also stalled over disagreement over four candidates.
The delegates agreed to set up a new committee tasked with overcoming the stalemate, the UGTT said in a statement overnight on Friday.
The committee comprising the head of the National Constituent Assembly (ANC), Mustapha Ben Jaafar, Ennahda chief Rached Ghannouchi and five opposition figures met on Saturday morning with UGTT secretary general Housine Abassi.
Ennahda and its opponents disagree on the frontrunners to become prime minister - Mohamed Ennaceur, 79, and Ahmed Mestiri, 88, two veteran politicians and former ministers.
Both are well respected and served under the late Habib Bourguiba, who led the fight for Tunisia's independence from its French colonial masters and served as its first president from 1957-1987.
Press reports said Ennahda and its secular coalition partner were backing Mestiri, while the opposition was in favour of Ennaceur.
"We consider Mestiri to be the man of the moment," said Ennahda spokesman Zied Laadhari. "He is equally distant from everyone."
But Bourad Amdouni, a representative for a coalition of leftist parties, said Mestiri "is not [physically] up to fulfilling the mission of prime minister".
Mestiri held several key portfolios in successive governments under Bourguiba - finance, justice, defence and interior - while Ennaceur is an expert on social affairs.
Prominent economists Mustapha Kamel Nabli and Jalloul Ayed had earlier also been named as frontrunners.
Whoever is chosen will have two weeks to form a government of independents to prepare for elections.
Current PM Ali Larayedh has pledged to step down so long as the timetable is respected.
The ANC, which finally met in plenary session on Saturday to discuss steps to speed up procedures after several delays, has until the end of November to draw up a new constitution and an electoral law.
The electoral timetable was set back after a court ruled that the selection by the ANC of an electoral commission, which had been slated for Saturday, must be postponed until a law creating it is passed.
But the office of President Moncef Marzouki announced on Saturday morning that he had promulgated the law.
The country's political crisis has been accompanied by a breakdown in security. On Wednesday, a suicide bomber blew himself up at a beach in the popular tourist resort of Sousse and minutes later security forces foiled another attack in nearby Monastir,
Tunisia has also been reeling from economic hardship - a driving force behind the 2011 uprising - with inflation running at more than six percent, a weak currency and a steep budget deficit of about 7.4 percent of gross domestic product.