Greece's president will meet with political party leaders in a last-ditch effort to broker a deal for a coalition government and avoid another general election.
Karolos Papoulias took the step on Saturday after socialist leader Evangelos Venizelos officially gave up the mandate to form a coalition government after three rounds of negotiations proved fruitless.
Papoulias's office announced that the president would meet on Sunday initially with the heads of the three parties that won the most votes in last Sunday's inconclusive elections - the conservative New Democracy, radical left-wing Radical Left Coalition (Syriza) and socialist PASOK.
He will then meet individually with the leaders of the other four parties that won enough votes for parliamentary seats - the right-wing nationalist Independent Greeks, the Communists, the extreme-right Golden Dawn and the moderate left Democratic Left.
The format was designed to bring everyone to the table, as Syriza leader Alexis Tsipras had threatened to boycott the talks rather than sit at the same table with Golden Dawn leader Nikos Michaloliakos.
In theory, the president's talks with the party leaders could drag until the scheduled date for the opening of the new parliament, on May 17. In practice, precedent shows that talks could take two or three days, George Katrougalos, a professor of constitutional law, told the Associated Press. It is also possible that an impasse could be reached on Sunday.
If Papoulias fails to broker a coalition agreement, Greece will have to hold new elections next month, most likely on June 10 or 17, prolonging the political uncertainty and bringing Greece's euro membership into question.
Venizelos was the third party leader to try to cobble together a governing coalition after elections last Sunday gave no party enough parliamentary seats to form a government. Voters furious at two years of harsh austerity measures taken in return for international bailouts worth 240 billion euro ($310 billion) rejected Greece's two formerly dominant parties, Venizelos' socialist PASOK and the conservative New Democracy, in favour of smaller parties on the left and right.
The turmoil has alarmed Greece's international creditors, who have stressed that the country must stick to the terms of its rescue deals if it hopes to continue receiving the funds that have been keeping it afloat since May 2010.
Whether Greece should adhere to the strict austerity measures required for the bailout loans or pull out of the deal has been at the heart of the wrangling over creating a coalition government.
Syriza leader Tsipras, whose party made massive gains to come second in Sunday's election, campaigned on an anti-bailout platform and insists any new government must cancel the austerity measures. He argues the terms are so onerous that they are giving the country's battered economy no chance of recovery.
But both Venizelos and Antonis Samaras, head of New Democracy, have slammed Tsipras' position as irresponsible. They say his policies would lead to disaster and force Greece out of the European Union's joint currency - something that none of the political leaders say they want.
Hopes had been raised that a solution could be found in the form of a partnership between New Democracy, PASOK and the smaller Democratic Left party of Fotis Kouvelis, whose 19 seats put it in a potential kingmaker position. But all three parties have insisted they cannot join forces without the support of Syriza, given its strong performance in the elections.
Handing back the mandate to the president, Venizelos said that, while there had been a meeting of minds between his party, Democratic Left and New Democracy, Tsipras was sticking to his position.
The latest opinion poll, published on Saturday in weekly financial paper "O Kosmos tou Ependyti" (Investor's World) confirms the recent trend showing Syriza overtaking New Democracy.
The poll estimates - by excluding declared don't knows and those who refuse to answer - that Syriza will win 25.5 per cent in a new election, up from 16.8 per cent it actually polled on May 6. New Democracy follows with 21.7 per cent, up from 18.9 per cent, and the socialists would gain 14.6 per cent, up from 13.2 per cent.
The Independent Greeks would get 10.5 per cent, marginally lower than the 10.6 per cent they got at the election. The poll projected losses for the Communists (5.3 per cent from 8.5 per cent) and Golden Dawn (4.8 per cent from 7 per cent).
Even if the results of the poll were to be confirmed, Syriza does not get enough votes to form a government on its own, although it would benefit from regulations that give the first party a bonus of 50 seats in the 300-member parliament, putting it in the dominant position to seek coalition partners among other anti-bailout parties.