Jaroslaw Kaczynski has been trying to convince voters that, as president, he would carry on his late brother's legacy. The strategy has had some success and, although he still trails Komorowski in opinion polls, one recent poll narrowed Komorowski's lead to as little as two points.

Both Kaczynski and his brother Lech have been known for their combative attitude toward Poland's historical enemies. But last month, Kaczynski surprised many people by delivering a conciliatory televised speech to Russia.

In the speech, he referred to his "Russian friends" and thanked the Russian people for their sympathy and support.

As political analyst Jacek Kucharczyk explains, this new approach represents a dramatic shift.

"If you look at the content of Lech Kaczynski's policies, it was basically this sense of threat to Poland coming both from external sources, from Russia, from Germany, from the European Union," noted Kucharczyk. "Obviously Kaczynski, if he wanted to increase his chances of success, had to play down all these ideas. He's trying to play a sort of moderate, right of the center candidate very much like Komorowksi."

Komorowski too has shied away from confrontational politics in his campaign.

As Komorowski told Polish television, he thinks that problems begin when politicians become more concerned about winning than about serving the state.

To win the election on Sunday, one of the candidates must secure at least 50 percent of the vote. Otherwise, the two top candidates will be facing each other again on July 4, in a runoff vote.