A historian and populist firebrand who boasted about his brawls with soccer hooligans has narrowly won Poland’s presidential election, in a political upset that could torpedo the centrist government’s efforts to unspool the legacy of authoritarianism in the country.

Karol Nawrocki, a populist conservative backed by U.S. President Donald Trump, has won Poland's presidential runoff election, according to official results released Monday.

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.