The leader of Greece's left-wing Syriza bloc has said he will try to form a coalition based on tearing up the terms of the EU/IMF bailout deal.
Alexis Tsipras, whose bloc came second in Sunday's vote, said Greek voters had "clearly nullified the loan agreement".
He has three days to reach a coalition deal and has told the two major parties to end their support for the austerity terms if they want to take part.
The European Commission and Germany say countries must stick to budget cuts.
European Commission President Jose Manuel Barroso said on Tuesday: "What member states have to do is be consistent, implementing the policies that they have agreed."
But, after French voters chose a new president on Sunday in Francois Hollande who has advocated greater focus on growth, EU leaders are to gather on 23 May for an informal meeting at which his proposals will be discussed.
German Chancellor Angela Merkel has written to Mr Hollande, saying that it is "up to us... to prepare our societies for the future and protect and advance prosperity in a sustainable way".Dramatic slide
The financial chaos has sparked huge social unrest in Greece and led to a deep mistrust of the parties considered to be the architects of austerity.