Conservative New Democracy leader Antonis Samaras (R) arrives at the Presidential Palace in Athens, Greece, May 13, 2012. Greek President Karolos Papoulias called the leaders of Greece's political parties to meet on Sunday, in a last-ditch effort to broker a deal for a coalition government. [Xinhua]

(From L to R) Greek socialist party PASOK leader Evangelos Venizelos, Conservative New Democracy leader Antonis Samaras, Greek President Karolos Papoulias and leader of Greece's radical leftist SYRIZA coalition Alexis Tsipras meet at the Presidential Palace in Athens, Greece, May 13, 2012. [Xinhua]

Alexis Tsipras (R), leader of Greece's radical leftist SYRIZA coalition, arrives at the Presidential Palace in Athens, Greece, May 13, 2012. [Xinhua]