Rafal Trzaskowski from Poland's ruling centrists Civic Coalition (KO) was seen ahead in a presidential election first round on Sunday, an exit poll showed, projecting a result that could boost Prime Minister Donald Tusk's pro-European government.

Trzaskowski was placed first with 30.8%, ahead of Karol Nawrocki, the candidate backed by the nationalist Law and Justice (PiS) party, who had 29.1%, the Ipsos exit poll showed.

If confirmed, the result would mean that Trzaskowski and Nawrocki will go head-to-head in a run-off vote on June 1 to determine whether Poland sticks to the pro-European path set by Tusk or moves closer to nationalist admirers of U.S. President Donald Trump.

In Poland, the president has the power to veto laws. A Trzaskowski victory in the second round would enable Tusk's government to implement an agenda that includes rolling back judicial reforms introduced by PiS that critics say undermined the independence of the courts.

However, if Nawrocki won then the impasse that has existed since Tusk became Prime Minister in 2023 would be set to continue. Until now, PiS-ally President Andrzej Duda has stymied Tusk's efforts.

If the exit poll is confirmed the other candidates in the first round, including Slawomir Mentzen from the far-right Confederation party, Parliament Speaker Szymon Holownia of the centre-right Poland 2050 and Magdalena Biejat from the Left, will be eliminated.

Two updated polls that take into account partial official results will be published later in the evening and early on Monday morning.