Poland's two presidential candidates faced off in their first one-on-one debate Sunday night in the elections to find a successor for Lech Kaczynski, who died in a plane crash in Russia in April, according to dpa. Bronislaw Komorowski of the centre-right Civic Platform party stressed Poland's need to play a stronger role in the European Union and was more liberal on social issues. Komorowski had received some 41 per cent of the vote in the first round of voting on June 20. Jaroslaw Kaczynski, of the right-wing Law and Justice party, was more hesitant to build relations with Russia and emphasized traditional values. Kaczynski, the identical twin brother of deceased President Lech, had received some 36 per cent of the vote in the first round. Poles will vote in a runoff on July 4 as there was no majority winner in the first round. The debate on Sunday - broadcast on five news channels in Poland - centered on three topics: foreign policy, the economy and domestic issues. Kaczynski was more conservative on social issues, saying when it came to in-vitro fertilization that he was a "Catholic who thinks an embryo is a person." Komorowski replied that, "everyone must decide in their conscience whether to reach for this method." There has been a heated debate in Poland, which is largely Roman Catholic, on whether the public health care system should pay for in- vitro fertilization. Kaczynski's brother died in the crash on April 10 in Smolensk, Russia, that also killed his wife and 94 other politicians and military brass. Kaczynski said he has always supported asking the Russian side to turn the investigation of the plane crash over to Poland. Kaczynski said the current situation was "unsatisfactory" with Russia and Poland cooperating on separate probes into the crash. Komorowski said there was a need to move into the future in relations with Russia, with programs like cultural events and youth exchanges. The debate was tense with both candidates at times going over their time limits or talking over each other. The candidates shook hands after the hour-long debate and quickly left the studio. A survey conducted on TVN 24's website after the debate showed 67 per cent of respondents believing Komorowski had won the debate. Some 26 per cent said Kaczynski won in the survey of some 64,000 respondents.