Leaders of the three biggest parties, each of whom had failed to form a government in the past week, convened at the presidential mansion, where President Karolos Papoulias had a last opportunity to implore them to form a coalition before he must call another election, probably in mid-June, Reuters reported.
The meeting broke up after less than two hours, and leaders said the discussions had hit a snag, though they expressed the hope that difficulties could be overcome.
The leftist Syriza party, a rising force that stands to gain even more ground if there are new elections, refused again to join or support the mainstream parties, New Democracy and Pasok, in a government that would seek to implement the austerity policies agreed with international creditors under Greece's latest bailout.
"They're asking for accomplices to austerity. We can't take part in this crime," Syriza leader Alexis Tsipras said after the talks, Dow Jones reported.
"Those who for two years have governed us and are responsible for the situation of society and the economy have not only not got the message ... they are continuing to blackmail and terrorize," he said, according to the Guardian.
"The three parties that have agreed with the goal of implementing the memorandum," he said, referring to the loan agreement, "have the majority. Let them go ahead. The demand that Syriza participate in their agreement is absurd. They are asking us to ignore the popular vote and our pre-elections pledges."
But conservative New Democracy leader Antonis Samaras told reporters coalition talks would continue while Socialist leader Evangelos Venizelos said there was "limited optimism" a deal might be reached as talks would continue with other parties.
Venizelos, Greece's former finance minister, renewed his call for a cross-party coalition to rule the country--and lashed out at Greece's radical leftists for blocking one--but said his party was ready to head for fresh elections if needed.
"Even now, despite the impasse at the meeting we had with the president, I hold on to some limited optimism that a government can be formed," said Venizelos, whose Pasok party was in power until recently but finished a humbling third in Sunday's election. But he warned time was running out.
"The moment of truth has come. We either form a government or we go to elections."
The New York Times reported that Papoulias was expected to meet with the leaders of several smaller parties on Sunday evening to try to persuade them to join a two-year unity government with Pasok and New Democracy aimed at enforcing the loan agreement -- but with a possible renegotiation of some of its terms.
Samaras blamed Syriza for blocking efforts to form a coalition.
The leftist leaders also sniped at each other.
Tsipras suggested that New Democracy and Pasok were going to form a coalition with a smaller group, the Democratic Left, CNN reported.
But the Democratic Left issued a statement calling his remarks "a disgrace," and accusing him of lying and slandering the smaller party.
"The three parties have 168 seats together," Tsipras said. "They can go ahead with that. They are pressuring us to participate, and that is an irrational and unprecedented request. They want us to give a fake sense of legalization."
The Democratic Left said it had not agreed to back a coalition without Syriza, and said of Tsipras: "His obvious inability to justify his stance should not lead him to slander and lie. This is an unethical political act on his part."
"The rage of Syriza is such that they would not allow such a government to stand even for a day," a Democratic Left official told the Times.
The head of the Communist KKE party Sunday called for the annulment of the loan deal, ruling out her party's participation in a coalition government, Dow Jones reported.
"We will introduce legislation in the Greek parliament, which is going to set out very specifically the elimination and annulment" of the deal, Aleka Papariga said after meeting with Papoulias.
Samaras placed first in the election last week but fell far short of an outright majority, punished by voters for backing a bailout package tied to harsh austerity cuts in the heavily indebted country.
Syriza, which campaigned against the bailout, finished a surprise second in the vote.
Both Samaras's New Democracy and Venizelos' Pasok -- which have taken turns to rule Greece for nearly four decades and jointly negotiated a bailout that requires deep cuts in public spending -- are eager to avoid facing the voters again.
Polls since the election show the balance of power tipping even further toward opponents of the bailout, who were divided among several small parties but now appear to be rallying behind Tsipras, a 37-year-old ex-Communist student leader.
If the vote is repeated, Syriza looks likely to place first, winning an automatic extra 50 seats at the expense of Samaras.
A poll released Saturday by Kappa Research and published in the To Vima newspaper found that Syriza has gained support since the elections and is now the country's most popular party, while New Democracy and Pasok have sunk further.
Syriza would receive 20.5 percent of the vote if elections were held now, up from 16.8 percent on May 6, while support for New Democracy fell to 18.1 percent from 18.85 percent in the elections, and Pasok would receive 12.2 percent, down from 13.2 percent.
"The denial to take part in a coalition government is not from Syriza but from the Greek people," Tsipras said last week. "The [loan agreement] has already been denounced by the Greek people."
If the next government rejects the bailout, EU officials say that would mean the end of loans that Athens needs to stave off bankruptcy and its possible exit from the euro single currency.
Polls show an overwhelming majority of Greeks reject the bailout but want to keep the euro. As many as 78.1 percent want the new government to do whatever it takes to keep their country in the currency, the Kappa Research poll showed.
Samaras and Venizelos have offered a broad coalition that would include Syriza and try to renegotiate some bailout terms, but Tsipras rejects that.
"It is obvious that there is an effort to bring about a government that will implement the bailout. We are not participating in such a government," Syriza spokesman Panos Skourletis said Saturday.
Another small leftist party - the Democratic Left led by lawyer Fotis Kouvelis - could provide enough seats to form a government with New Democracy and Pasok, but has said it will not do so unless the coalition also includes Syriza.
Greeks seem resigned to returning to the polls.
"Why would we believe they'll agree on something? All they care about is being in power and we're sitting here not even able to pay our electricity bills," said Maria Kissou, 53, a corner shop owner in Athens. "Let us go to elections again."
Kissou voted for Tsipras on May 6.
"He's young, I like him because at least he's trying to renegotiate with the Europeans," Kissou said.
Supporters of the two establishment parties will be hoping that if a new election is held, Greeks will be frightened of the prospect of leaving the euro and return to the fold.
"Country on a dangerous path," the conservative daily Kathimerini warned on its front page.
Papoulias will also meet Sunday evening with leaders of parliament's small parties, which for the first time include the far right, neo-fascist Golden Dawn.
In one of the unfolding drama's many sub-plots, Greeks will watch with interest to see how the president, a revered 82-year-old veteran of the World War II anti-Nazi resistance, receives a group whose members give Nazi-style salutes.
The constitution sets no deadline for Papoulias to complete his search for a deal and he has given no indication how long he will spend trying before he calls a new election.