The victory of Karol Nawrocki, who is backed by the previous right-wing governing party, will complicate Prime Minister Donald Tusk’s efforts to advance his liberal agenda.
A nationalist who is hostile to Poland’s centrist government has eked out a narrow win in a runoff election for the presidency, delivering a severe setback to Prime Minister Donald Tusk, according to official results released on Monday.
The winner, Karol Nawrocki, a historian and former boxer who is backed by Poland’s previous governing party, Law and Justice, captured 50.9 percent of the vote on Sunday, adding momentum to a right-wing populist movement in Europe. President Trump had endorsed Mr. Nawrocki before the election.
He came out just ahead of Rafal Trzaskowski, the liberal mayor of Warsaw, who was supported by Mr. Tusk’s party, Civic Platform. Mr. Trzaskowski had 49.1 percent of the vote.
That outcome leaves Poland bitterly divided with two power centers — the government and the presidency — pulling in opposite directions.
The two sides agree that Poland should provide weapons to Ukraine for its war against Russia and build up its military, but diverge sharply on most domestic issues, including abortion, which was all but banned during eight years under the right-wing Law and Justice government.
The Polish runoff came just two weeks after voters in Romania rejected a nationalist candidate in a presidential election, a result that raised the hopes of Polish liberals that Europe’s right-wing populist wave was receding.
