Greek Socialist leader Evangelos Venizelos says progress is being made in the country's third attempt to form a new coalition government, after the Radical Left and conservative New Democracy parties failed to do so this week.

Venizelos, whose PASOK party came in a distant third in Sunday's elections, said Thursday steps were made in his talks with members of the Democratic Left, a small left-wing party that has enough votes to give him the majority he needs to lead.

If a deal is not reached, President Carolos Papoulias will be forced to call on parties to form an emergency coalition.

If that cannot be done by May 17, new elections will be called.

New Democracy won the most parliamentary seats in Sunday's election, followed by the Radical Left and PASOK. But no party won enough seats to be able to put together a new government on its own.

Greek voters punished both PASOK and New Democracy for having pushed through tough economic austerity measures in return for huge international loans from Greece's European neighbors and the International Monetary Fund to avoid a default.

Radical Left leader Alex Tsipras had called on the two parties to renounce their support for the deep spending cuts but could not get enough support in parliament to hammer out a coalition.

EU leaders are pressuring Greece to carry through with the austerity plans.