Evangelos Venizelos, the Greek Socialist party leader, has been unable to form a national unity government after holding last-ditch talks with rivals, party officials have said.
“Venizelos will return the mandate tomorrow to President Karolos Papoulias,” a senior Socialist PASOK party official told Reuters news agency.
Separately, Papoulias’s office said he would meet Venizelos on Saturday on 1000 GMT.
Earlier in the day, Venizelos held talks with centre-right New Democracy leader Antonis Samaras and other political leaders in a bid to form a coalition.
The leader of anti-bailout Left Coalition (Syriza) party said he would not join a national unity government with the Socialist leader.
“It is not the Left Coalition that has refused this proposal, but the Greek people who did so with their vote on Sunday,” Alexis Tsipras said after talks with Venizelos.
The moderate Democratic Left party, which won 19 seats in Sunday’s election, said it could not join any coalition that did not include Syriza.
“We have made it clear, the Democratic Left party will not take part in a (coalition) government of New Democracy and PASOK,” Fotis Kouvelis, party leader, said.
Venizelos, whose party came a distant third in last week’s inconclusive elections, winning 41 seats in the 300-seat parliament, had earlier said he wanted to create a unity government that would keep Greece in the eurozone – an aim echoed by Kouvelis.
Venizelos’ efforts follow the failures of New Democracy, which gained more than 100 seats, and the anti-austerity leftwing Syriza party, which finished second, to form governments.
Greece is now deep into political crisis that could kill off reforms and eventually force the debt-laden nation to leave the euro single currency union.
Wolfgang Schaeuble, the German finance minister, said in an interview published on Friday that the eurozone would cope without Greece.
“We want Greece to remain in the eurozone,” he told the regional Theinische Post. “But it also has to want this and to fulfill its obligations. We can’t force anyone. Europe won’t sink that easily.”