A pivotal presidential election on Sunday in Poland was too close to call, with exit polls putting the two contenders nearly neck and neck as voting ended and an official count of the ballots began.
Rafal Trzaskowski, the liberal mayor of Warsaw, appeared to be narrowly ahead in the runoff election, but by such a small margin that it was unclear whether he would prevail in the official vote tally due on Monday.
Mr. Trzaskowski nonetheless claimed victory.
“Dear ladies and gentlemen — we won!” he declared to supporters Sunday evening in Warsaw. “I think that the term ‘razor-thin victory’ will enter the Polish language.”
The results of usually reliable exit polling, broadcast by public and private television stations Sunday evening after polling stations closed, gave Mr. Trzaskowski a tiny advantage, with 50.3 percent of the vote. His rival, Karol Nawrocki, a nationalist historian backed by Poland’s previous right-wing governing party, Law and Justice, had 49.7 percent.
Mr. Nawrocki told his own supporters after the exit poll data came out that the official results would show him to be the victor. “Dear people, we will win,” he said. “Tonight we will win and save Poland.”
The turnout was 72.8 percent, the highest in a Polish presidential election since the first free and direct vote for the presidency in 1990, when Lech Walesa, the Solidarity trade union leader, won after the collapse of communism.
The election has been widely viewed as a test of whether populist nationalism is a rising or receding force in Europe and beyond. A hard fought campaign drew in supporters and foes of President Trump on both sides of the Atlantic.
The Trump administration, along with Prime Minister Viktor Orban of Hungary and other right-wing politicians, including the defeated Trump-admiring nationalist candidate in a recent presidential election in Romania, were rooting for Mr. Nawrocki. Europe’s mainstream political forces supported Mr. Trzaskowski.
The election hinged on the question of whether Polish voters want a president who can work with the sitting government of Poland’s centrist prime minister, Donald Tusk, or one who opposes it. The closeness of the race highlighted Poland’s polarization between right-wing nationalist forces opposed to Mr. Tusk and centrists who support him.
The election of Mr. Trzaskowski, who was backed by Mr. Tusk’s party, Civic Platform, would likely end a long period of political deadlock that began when Law and Justice lost its majority in Parliament in a 2023 election but retained control of the separately elected presidency.
The presidency is a largely ceremonial role, but the president has veto power over legislation passed by Parliament. The departing, term-limited president, Andrzej Duda, used this power to obstruct efforts by Mr. Tusk’s government to reverse the legacy of eight years of populist rule by Law and Justice.
A win for Mr. Nawrocki would continue and even harden this deadlock.
Anatol Magdziarz contributed reporting.
