Nationalist opposition candidate Karol Nawrocki narrowly won Poland's presidential election, results showed Monday, delivering a major blow to the centrist government's efforts to cement Warsaw's pro-European orientation.

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.

Eurosceptic Nawrocki's win can deliver considerable setbacks to former European Council President Tusk's pro-EU government.