World powers have urged Greece to move quickly as coalition talks inch towards a possible national unity cabinet after an election win by pro-bailout parties that eased fears of a Greek eurozone exit.
The Harvard-educated conservative leader Antonis Samaras won the election with his New Democracy party and held coalition talks after President Carolos Papoulias urged parties that a deal on Monday was "a categorical imperative".
"The country cannot remain ungoverned even for an hour," Papoulias said.
The 61-year-old Samaras, a former foreign minister, said: "A national agreement is an imperative... We need to resolve the question immediately."
But his most likely coalition ally, Evangelos Venizelos of the socialist Pasok said he wanted a national unity cabinet including other leftist parties.
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"The best thing would be to form a government of national responsibility... Discussions on the formation of a government should be completed on Tuesday."
Samaras said after the meeting that he had struck an agreement with Venizelos on the formation of "a government of national salvation" by Wednesday.
Second-placed radical leftist Syriza, which has called for an unpopular EU-IMF bailout deal that has imposed harsh austerity conditions on many Greeks to be torn up, has already ruled out joining any coalition led by New Democracy.
Samaras' conservatives won 129 of the 300 parliamentary seats in Sunday's historic vote, Syriza won 71 seats, Pasok 33, Independent Greeks 20, the neo-Nazi Golden Dawn 18, Democratic Left 17 and the Communist Party 12.
With many Greeks increasingly fed up with austerity, more than a quarter of the vote in the election went to Syriza. Its firebrand leader Alexis Tsipras vowed on Monday that he would "keep the government in check".
Samaras has promised to respect Greece's international engagements but also said on Monday that there should be amendments to the harsh conditions of the bailout deal "so the Greek people can escape from today's torturous reality".
Key EU player Germany has said there could be an extension of a deficit cutting deadline but New Democracy's campaign promises appear to go further, including a reduction in property and sales taxes and a freeze in pension and salary cuts.
"Elections cannot call into question the commitments Greece made. We cannot compromise on the reform steps we agreed on," German Chancellor Angela Merkel warned in the Mexican resort of Los Cabos just ahead of the G20 summit.
