WARSAW, June 1 (Reuters) – Eurosceptic Karol Nawrocki established a lead in Sunday’s presidential election in Poland, late exit polls showed, with the ballot seen as a test of the nation’s support for a pro-European course versus Donald Trump-style nationalism.

A late exit poll by Ipsos for broadcasters TVN, TVP and Polsat showed Nawrocki at 51% and his rival, liberal Warsaw Mayor Rafal Trzaskowski, at 49%. Readings published just after voting ended had Nawrocki losing at 49.7% to 50.3%. Official results were due on Monday.

Nawrocki, 42, an amateur boxer who ran a national remembrance institute, campaigned on a promise to ensure government economic and social policies favour Poles over other nations, including refugees from neighbouring Ukraine.

While Poland’s parliament holds most power, the president can veto legislation, and the vote was being watched closely in Ukraine as well as Russia, the United States and across the European Union.

Both candidates agreed on the need to spend heavily on defence as Trump, the U.S. president, is demanding from Europe and to continue supporting Ukraine in its fight against Russia’s three-year-old invasion. Poland is a member of the 32-nation North Atlantic Treaty Organization security alliance.

But while Trzaskowski sees Ukraine’s future membership of NATO as essential for Poland’s security, Nawrocki said recently that if he were president he would not ratify it because of the danger of the alliance being drawn into war with Moscow.

Russia has demanded that NATO not enlarge eastward to include Ukraine and other former Soviet republics as a condition of a peace deal with Kyiv, sources have said.

Nawrocki has presented the ballot as a referendum on the broad coalition government of pro-Europe Prime Minister Donald Tusk, the leader of the Civic Coalition (KO) party who took office about 18 months ago.

“This will be a good counterweight to the government,” said Mateusz Morawiecki, who was prime minister in the nationalist Law and Justice (PiS) government that lost power in 2023. Although technically an independent, Nawrocki was backed by PiS in the election.

Trzaskowski, 53, had promised to help Tusk complete his government’s democratic reforms, which they both say aim to repair an erosion of checks and balances under the former PiS government.

Trzaskowski’s campaign initially proclaimed victory on Sunday and did not immediately comment after poll readings showed a move in Nawrocki’s favour.

The first round of the election on May 18 saw a surge in support for the anti-establishment far-right, suggesting that the KO-PiS duopoly that has dominated Polish politics for a generation may be starting to fracture.

Nevertheless, after a tumultuous campaign in which Nawrocki in particular faced a slew of negative media reports about his alleged past conduct, once again candidates representing the two main parties faced off in the second round.

Nawrocki dismissed accusations of wrongdoing in his acquisition of a flat from a pensioner and participation in mass organized fights among football hooligans.

Social issues were also at stake in the election. Trzaskowski has said he wanted to see Poland’s near-total ban on abortion eased, something that outgoing nationalist President Andrzej Duda strongly opposed.

A win by Nawrocki will likely mean that Hungarian Prime Minister Viktor Orban and Slovakia’s Robert Fico gain an ally in central Europe. His victory could lend momentum to the Czech Republic’s eurosceptic opposition leader and former Prime Minister Andrej Babis who leads opinion polls ahead of an October election.

U.S. Homeland Security Secretary Kristi Noem spoke in Nawrocki’s favour in May, telling a conservative gathering in Poland that he “needs to be the next president.” (Reporting by Alan Charlish, Kuba Stezycki, Marek Strzelecki, Pawel Florkiewicz, Anna Wlodarczak-Semczuk, Anna Koper, Karol Badohal and Barbara Erling; Writing by Justyna Pawlak; Editing by Philippa Fletcher, Sophie Walker, Frances Kerry, Nia Williams and Cynthia Osterman)