The governing conservative party of PM Costas Karamanlis has won Greece's general election, retaining a slim majority in parliament.
Mr Karamanlis is claiming victory - but the margin is still unclear
George Papandreou's socialist Pasok party trailed Mr Karamanlis's New Democracy party by nearly four percentage points.
With 99% of the votes counted, New Democracy's majority has been cut to 152 seats in the 300-seat parliament.
The vote was overshadowed by forest fires that killed dozens in August.
Pasok had 38.1% of the vote giving it 102 seats and Mr Papandreou is under pressure to resign for failing to capitalise on criticism of the government's response the forest fires.
Mr Karamanlis told his supporters that the party had been given a "clear mandate" to continue reforms.
"I feel doubly responsible to be more effective and avoid mistakes," he said.
Minutes earlier, Mr Papandreou had made a speech thanking his supporters for showing their "love and trust" in him, adding: "Pasok fought a battle and lost it."
With Mr Papandreou under pressure to resign after his second election defeat in four years, former Culture Minister Evangelos Venizelos has already declared his interest in becoming party leader.
Mr Karamanlis had been expected to triumph in the poll, after calling elections six months before the end of his term of office.
But his support fell when many Greeks felt the government was slow to react to the forest fires, which killed 65 people.
However, the BBC's Malcolm Brabant in Athens says the prime minister rallied the nation with a steady, competent and compassionate display during the election campaign.
Voting is compulsory
A total of 21 parties are involved in 56 constituencies
A total of 300 deputies are elected for four year
Forty seats awarded to party with largest number of votes to make majorities more secure
Other 260 seats divided on percentage of vote
Mr Karamanlis has pledged to use his new four-year term to improve the economy, fight poverty, raise pensions and create a social state for the future.
But with only four more seats than the combined opposition, he may have trouble pushing through his reforms.
He has also told the victims of the fires that the government's commitment to them would be fulfilled completely.
The Papandreou and Karamanlis families have dominated the Greek political scene for most of the past 50 years.
But both main parties suffered a fall in votes this year, with the three smaller parties from the far left and right gaining support.