Radical leftist leader Alexis Tsipras says he has failed to forge a coalition to end Greece's postelection deadlock.
He says he will return the mandate on May 10 to President Karolos Papoulias.
Tsipras's antiausterity Syriza party finished second in the May 6 national elections, which left no party with enough seats to govern alone.
If no deal can be reached in the next days, new elections will be called next month.
Earlier on May 9, Socialist leader Evangelos Venizelos, whose pro-austerity party came in third in the elections, said President Papoulias will ask him to form a new government.
Antonis Samaras, the leader of the other pro-austerity party, the New Democracy, which won the elections, also said on May 9 after meeting Tsipras that he did not agree to a coalition with Syriza, because its demands would bankrupt Greece.
Samaras on May 7 had also failed to build a coalition.
If no deal can be reached in the next days, new elections will be called next month.
Athens has to pass new austerity measures worth 14.5 billion euros ($18.8 billion) next month to qualify for the next installment of EU-IMF bailout funds.
He says he will return the mandate on May 10 to President Karolos Papoulias.
Tsipras's antiausterity Syriza party finished second in the May 6 national elections, which left no party with enough seats to govern alone.
If no deal can be reached in the next days, new elections will be called next month.
Earlier on May 9, Socialist leader Evangelos Venizelos, whose pro-austerity party came in third in the elections, said President Papoulias will ask him to form a new government.
Antonis Samaras, the leader of the other pro-austerity party, the New Democracy, which won the elections, also said on May 9 after meeting Tsipras that he did not agree to a coalition with Syriza, because its demands would bankrupt Greece.
Samaras on May 7 had also failed to build a coalition.
If no deal can be reached in the next days, new elections will be called next month.
Athens has to pass new austerity measures worth 14.5 billion euros ($18.8 billion) next month to qualify for the next installment of EU-IMF bailout funds.