He edged out Jaroslaw Kaczynski, the twin brother of the deceased president, who received 36.7 percent, according to official results from more than 94 percent of polling stations.
Kaczynski's campaigning in the past few weeks has helped close what was just recently a much wider gap in the polls, and if the trend continues, he could come from behind to beat Komorowski when the two compete in a run off on July 4.
A turn left
Another surprise was the unexpectedly good performance of Grzegorz Napieralski, the leader of the centre-left Democratic Left Alliance (SLD). Mr. Napieralski won 13.7 percent of the vote, despite the polls that showed his support ranging between 3 and 7 percent.
This is important, analysts say, because the left-wing vote could very well be a deciding factor on July 4.
Given their praise of Napieralski on the election night, it seems that Komorowski and Kaczynski have already started to woo left-wing voters with an eye on the run-off, analysts say.
"I would like to congratulate Grzegorz Napieralski on his remarkable score. It is surely something he can be proud of, and I would like to believe that this great achievement will be the beginning of better times for the Polish left,” Komorowski told his supporters on the election night. "The Polish left is absolutely indispensable on Poland’s political scene,” he added.
Kaczynski thanked Napieralski for a good election fight. But according to the latest polls, Napieralski’s electorate is likely to vote for Komorowski in the run-off, with only about 10-15 percent of left-wing voters claiming they would back Kaczynski's right-wing Law and Justice party (PiS).
"A formal agreement between the left and the Civic Platform before the upcoming vote could be a preface to a possible government coalition in the future,” Aleksander Kwasniewski, Poland’s former president from the Democratic Left Alliance, told the Gazeta Wyborcza newspaper.
A vote tinged by grief
Shadowed by Poland’s recent national tragedy, the vote took place more than two months after the death of Polish President Lech Kaczynski. On April 10, a government Tu-154 plane carrying the president, his wife, and a group of senior political and military officials crashed near Smolensk in western Russia, killing all 96 passengers and crew members.