Poland has elected Karol Nawrocki, a nationalist conservative, as its next president — a win that signals a turn to the right in one of the European Union's member states.

Karol Nawrocki, a historian who has flaunted his ties with the U.S. president, has promised to block a Ukrainian accession to NATO.

Poles awakened Monday to a clear albeit close result that returns a nationalist politician to the presidency who has pledged to hinder the centrist, pro-EU government for the remainder of its term.