WARSAW -- Rafal Trzaskowski, mayor of Warsaw, was leading by a narrow margin in Poland's presidential runoff on Sunday, according to exit polls.

According to the exit poll by Ipsos, Trzaskowski, candidate of the ruling Civic Coalition (KO), received 50.3 percent of the vote, while his rival Karol Nawrocki, an independent candidate backed by the opposition Law and Justice (PiS) party, received 49.7 percent. The voters' turnout is estimated at 72.8 percent.

According to the exit poll by the Polish Nationwide Research Group, Trzaskowski led the runoff with 50.17 percent of the vote, while Nawrocki received 49.83 percent.

Since the margin of error for exit polls is typically ±2 percentage points, the results remain within the statistical margin of error and the final winner has yet to be determined.

Final results are likely to be announced on Monday morning or early afternoon, according to the Polish National Electoral Commission (PKW).

A closely contested first round was held on May 18, in which Trzaskowski secured 31.36 percent of the vote, followed by Nawrocki with 29.54 percent. As no candidate secured more than 50 percent of the vote in the first round, the election proceeded to a runoff.