Costas Karamanlis, the Greek prime minister, has called an early general election as he seeks a fresh mandate to deal with the economic crisis.
Karamanlis made the announcement on Wednesday, despite the opposition of several members of his cabinet.
Karamanlis said he would ask President Carolos Papoulias to dissolve parliament on Thursday. The election will be held on October 4, a senior government official said.
"We are asking Greeks to trust us to take it out of a difficult economic crisis, and I am asking for a fresh political mandate to do this," Karamanlis said in a televised address to the nation.
"If we do not act immediately, then the consequences will be great, with 2010 a difficult year ahead for the economy."
The move is risky as his scandal-plagued conservative New Democracy government trails the main opposition socialist Pasok party by about six percentage points in opinion polls.
The conservatives, who currently have a one-seat majority in parliament, have suffered months of scandals and their popularity has sunk lower after criticism of their response to recent wildfires which hit the outskirts of the Greek capital last month.
The socialists, themselves burdened with scandals during decades in government, have long pressed for an early vote and would have been in position to force one in March.
Pasok advocates a "green growth" economic model.
They have said that if the election fails to win an outright majority, they will call for a second vote under a revised electoral law that makes it easier to form a government with fewer votes.
Seen by investors as the euro zone's riskiest bet, Greece is struggling to cope with the global slowdown that is threatening to push its economy into recession this year while its national debt is ballooning.