Pro-EU Mayor Takes Slim Lead in Poland Vote, Exit Polls Show (1)

The centrist mayor of Warsaw took a slim lead in Poland’s presidential election over a nationalist candidate backed by Donald Trump, giving a boost to the country’s pro-European Union government, exit polls show.

Rafal Trzaskowski won 50.3% of the vote, while Karol Nawrocki took 49.7%, according to a nationwide exit poll on Sunday, which has a margin of error of about 2 percentage points. Results will be tallied through the night, with official results due Monday.

The ballot will determine whether one of the EU’s fastest-growing economies and one of NATO’s biggest defense spenders remains a reliable partner within ...