Polish presidential candidate Bronislaw Komorowski was leading in the second round of elections, according to partial poll results after voting stations closed Sunday, dpa reported.
Komorowski, of the centre-right Civic Platform party, had won 50.61 per cent of the vote in the runoff, said the state election commission, based on 20.94 per cent of the polls reporting.
His opponent Jaroslaw Kaczynski, of the rightwing Law and Justice party, had received 49.39 per cent of the vote.
Voter turnout was some 54.59 per cent, the commission said.
The Polish presidential elections were held early in order to find a successor to Lech Kaczynski, who died in a plane crash in April. Full official results are expected early Monday.
"Our Polish democracy has won," Komorowski said Sunday. "And even though we'll have to wait for the big bottle of champagne tomorrow, I think we have enough reason for pride and joy."
The campaign had been "especially difficult because it took place in the shadow of the tragedy," he said.
Kaczynski, the twin brother of Lech Kaczynski, spoke to his supporters in Warsaw, saying his party now had a chance to win in the parliamentary elections scheduled for 2011.
"I congratulate the winner, I congratulate Bronislaw Komorowski," Kaczynski said. "But most of all I want to sincerely thank all those who participated in these elections, and those who supported us. There are many of them. So many that we can surely say that Poland has changed."
Sunday's election follows a first round of voting on June 20, in which no candidate secured a majority.
Long lines formed at polling stations on the Baltic coast, northern Poland, where thousands cast their vote during their vacations. There were also crowds in Hurghada, Egypt, another popular tourist destination for Poles, reported TVN 24.
Both candidates had cast their votes by the afternoon: Kaczynski in his native Warsaw, and Komorowski in Mackowa Ruda, a rural retreat in northeastern Poland where he was spending the weekend.