Finland's ruling Centre Party is starting talks on forming a new coalition government following its narrow success in Sunday's election.
After his win, Mr Vanhanen now faces difficult talks
The party of Prime Minister Matti Vanhanen gained 51 parliamentary seats, one more than its closest rival, the Conservative National Coalition.
The Social Democrats, who formed part of the outgoing centre-left government, were beaten into third place.
The party could now go into opposition if Mr Vanhanen realigns his coalition.
"We did it!" Mr Vanhanen said after the official results were announced.
"In an election it's always easy to win from the opposition, but the most difficult thing is to renew one's victory," he told jubilant supporters in Helsinki.
The Centre Party took 23.1% of the vote, the National Coalition gained 22.2% and the Social Democrats 21.5%.
Shift to the right
Conservative leader 35-year-old Jyrki Katainen said his party could not be sidelined from talks on forming a new government.
"The people wanted the Conservatives to grow - that should also be reflected in the government," he said.
"I think it would be very odd if we were not in the next government."
Mr Vanhanen has so far been unwilling to discuss what would happen if support swung behind the Conservative party.
Talks on the formation of the next government would be "very difficult", he said.
The largest party in the polls traditionally forms a parliamentary majority and names the prime minister. Since 2003, the Centre Party has governed alongside the Social Democrats and the small Swedish People's Party.
Social Democratic Party Secretary Maarit Feldt-Ranta said the Centre Party would initiate talks. "The ball is in their court," she said.
The Social Democratic Party, which now has 45 MPs, lost eight seats in the 200-strong parliament.
Mr Vanhanen is due to tender his government's resignation on 28 March; the formation of the new government is expected in mid-April.
Its first test will be nationwide pay talks in the next few months. It will also have to consider proposals for possible limits on presidential powers, which currently include a role in foreign affairs.
Political analysts see a swing to the right in Finland as inevitable.
"There is no chance to bypass the National Coalition," Finland's biggest selling broadsheet newspaper commented.
"It is clear we will have a centre-right government," Risto Penttila, director of the Finnish Business and Policy Forum said.
"It is notable that not only Finland has turned to the centre-right, but that it is part of a wider trend."
Finland's election comes six months after Swedes voted out the Social Democrats and elected a centre-right coalition.