"This is a victory for all Europe," he said. "I call upon all political parties who share these objectives to join forces and form a stable new government."
Samaras repeated campaign promises to honor the country's bailout pledges.
"We will work together with our partners in Europe in order to supplement the current policy mix with growth enhancement policies," he said. "We are determined to do what it takes and do it fast."
Greece's broad-circulation Ta Nea daily said in an editorial Monday that party leaders — including Syriza's Alexis Tsipras — must respect voters' manifest desire for a coalition government.
"The country cannot waste a day," the paper said. "It is clear from the arithmetic that after New Democracy's victory a government can even be formed by two parties. But from a political viewpoint that will not suffice. All parties that say they believe in the country's European future must actively prove their respect for the message of the elections."
Athens resident Christina Stathaki said she was not satisfied with Sunday's result, particularly as it confirmed extremist Golden Dawn's high standing.
"Practically a fascist party, Golden Dawn, has from now on established itself in Parliament," she said. "For me, that's what hurts."
The United States welcomed Sunday's result. "We hope this election will lead quickly to the formation of a new government that can make timely progress on the economic challenges facing the Greek people," the White House said in a statement.
Power-sharing negotiations could be tough. Socialist PASOK leader Evangelos Venizelos, who spent months negotiating bailouts as Greece's finance minister, has suggested dumping the usual procedure of each party seeking coalition partners. He proposed a four-party coalition between New Democracy, Syriza, PASOK and Democratic Left, which was in sixth place with 6.3 percent of the vote and 17 seats.
"There is not one day to lose. There is no room for party games. If we want Greece to really remain in the euro and get out of the crisis to the benefit of every Greek family, it must have a government tomorrow," Venizelos said.
PASOK officials said Venizelos would insist on Syriza joining any future coalition, despite its anti-bailout stance — although the move could simply be a negotiating tactic to convince the public that Syriza was unwilling to play a constructive role in pulling Greece out of its crisis.
Tsipras, a 37-year-old former student activist, has ruled out such a possibility.
Tsipras phoned Samaras on Sunday night to congratulate him on his victory and vowed that his party would remain outside the government.
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