Polish voters handed Prime Minister Donald Tusk's centre-right Civic Platform four more years in power, exit polls showed, paving the way for him to pursue cautious economic reforms and closer ties with the rest of the EU.
An exit poll showed Mr Tusk's pro-business party was on course to win 39.6% of votes in a parliamentary election, short of an absolute majority but far ahead of Jaroslaw Kaczynski's nationalist-conservative Law and Justice party on 30.1%.
It is the first time a ruling party has been re-elected in the country of 38 million since the fall of communism in 1989.
Financial markets are expected to welcome the result, which points to four more years of relative political and economic stability in the European Union's largest eastern member state at a time of deepening crisis in the eurozone.
"I wanted to thank all of those who voted for us and those who didn't because we will be together bearing responsibility for Poland for four more years," Mr Tusk, 54, said in a victory speech to cheers at his party's headquarters.
Mr Kaczynski conceded defeat and the Peasants' Party, Tusk's junior coalition partner for the past four years, said it was ready to renew the alliance.
Projections based on the exit poll showed the two parties would have enough seats to secure a majority in the Sejm or lower house.
Polish President Bronislaw Komorowski, a former Civic Platform lawmaker, is now expected to ask Mr Tusk to form a government but he said he must first wait for the official election results, expected on Tuesday evening.
