WARSAW — Centrist Rafał Trzaskowski was very slightly ahead of his populist rival Karol Nawrocki in Poland’s presidential election, according to an exit poll released after voting ended Sunday evening, leading by 50.3 percent to 49.7 percent.

However, that is within the exit poll’s 2 percentage point margin of error, so it is impossible to say who the winner is. A clearer picture will emerge when an updated poll by the IPSOS organization is released at 11:30 p.m. The electoral commission says final results of the vote count will be announced on Monday.

If the result holds and Trzaskowski is the winner, it would be a big victory for Trzaskowski’s party boss, Prime Minister Donald Tusk, and his effort to continue reintegrating Poland into the EU.

Despite the uncertainty over the outcome, Trzaskowski was treating it as a victory.

“I want to thank Poles for their vote,” he told cheering supporters moments after the exit poll was released, adding: “I will be your president!”

This article has been updated.