Israeli Prime Minister Benjamin Netanyahu and parliamentary Speaker Benny Gantz missed a midnight deadline to form a unity government early on Thursday, prolonging the country's political deadlock.
The right-wing Mr Netanyahu and centrist Mr Gantz, Israel's former army chief, have gone head to head in three stalemated elections over the past year.
After the most recent vote last month, both men fell short of a majority and neither had a clear path towards a viable governing coalition.
With the Covid-19 pandemic resulting in more than 12,000 confirmed infections in Israel, there have been continued, widespread calls for an interim emergency alliance.
A deal between the two would given Israel its first stable government since December 2018.
President Reuven Rivlin said that if they failed to meet his midnight deadline he would likely ask Israel's Parliament, the Knesset, to nominate a candidate for prime minister.
Throwing the decision to the Knesset would almost certainly create more uncertainty and possibly another election.
Mr Gantz, who leads the Blue and White alliance, was given a deadline of four weeks to form a government after the March vote, when a received a majority of recommendations from the 120-member Knesset.
But he was unable to because of the bitter divisions within the anti-Netanyahu parliamentary bloc.
After being elected Knesset Speaker, Mr Gantz pledged to use the rest of his grace period to seek a deal with Mr Netanyahu.
Minutes before that mandate expired at midnight on Monday, Mr Gantz and Mr Netanyahu asked Mr Rivlin for an extension, insisting they were close to a deal.
The president gave them until the end of Wednesday.
Israel was shut down until Wednesday evening for the last day of the Passover holiday.
The sides were reportedly meeting late into the night once the holiday ended, but Blue and White and Mr Netanyahu's Likud both declined to comment on the status of the talks.
Mr Gantz's attempt to seek a deal with Mr Netanyahu triggered the break-up of his Blue and White alliance.
But he said it was necessary to ease the political deadlock and strengthen Israel's ability to confront the pandemic.
By becoming Speaker, Mr Gantz all but conceded that Mr Netanyahu would remain prime minister, at least through the first part of any unity deal.
The two have reportedly discussed a range of power-sharing arrangements including one that would see Mr Gantz take over as premier after some months, or years.
But obstacles emerged during coalition talks.
The sides were reportedly split over the choice of the justice minister, who would oversee a corruption case against Mr Netanyahu.
The veteran leader, in power since 2009, became the first Israeli prime minister to be indicted in office after being charged with bribery, fraud and breach of trust.
Mr Netanyahu denies the allegations.
There has also reportedly been friction about implementing US President Donald Trump's widely condemned Middle East peace plan.
Mr Netanyahu wants fast action on the plan, in which Israel would annex strategically crucial parts of the occupied West Bank in defiance of international law.
Mr Gantz has been more cautious about the Trump plan, which was rejected by the Palestinians.
