Nearly 16 weeks after inconclusive elections left Spain without a proper government, and as acrimony between party leaders intensifies, negotiators from all three groupings will sit down at 4.30pm in Madrid to try and unblock the political paralysis gripping the country.
"We are going with the clear will to do our utmost to obtain a government... but also knowing that it's very difficult, that we are political parties that are far apart from each other," Meritxell Batet, part of the Socialists' negotiating team, told Spanish radio.
And it will be all the more difficult following acrimonious exchanges in parliament between Podemos chief Pablo Iglesias and Ciudadanos leader Albert Rivera on Wednesday.
Accusations of cronyism, intolerance, shady party financing... Both traded barbs a mere 24 hours before the three-way meeting, prompting concern over how two parties already far apart ideologically could sit down for civil talks.
Antonio Hernando, who heads up the negotiating team of the Socialists - the party tasked with forming a government - tried to play down these differences in an interview with the El Pais daily.
"Attitudes are different in public and in private, whether there are cameras and microphones or not. There won't be any in today's meeting," he said.
And the clock is ticking. If no power-sharing agreement is found by May 2nd - or in just under a month - new elections will be called, most likely for June 26th.
This would extend the paralysis that has gripped Spain since December's general elections, at a time when the country is emerging limping out of a damaging financial crisis.
The polls put an end to the traditional two-party system as voters fed up with austerity, unemployment and corruption scandals flocked to new parties, leaving a hung parliament divided among four main groupings, none of them with enough seats to govern alone.
The Socialists were tasked with trying to form a government after acting Prime Minister Mariano Rajoy - whose conservative Popular Party came first in elections - gave up attempts to do so due to lack of support from other groupings.
The Socialists reached a pact with Ciudadanos, which came fourth.
But that does not give them enough seats to push a government through, and they need the support of Podemos - which came third in the election, giving it considerable sway in coalition negotiations.
Podemos which has recently lost ground in opinion polls, had refused to sit down for negotiations with the Socialists if Ciudadanos was involved, but last week agreed to do so.