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.

Conservative Karol Nawrocki won Poland’s weekend presidential runoff election, according to the final vote count on Monday. Nawrocki won 50.89% of votes in a very tight race against liberal Warsaw Mayor Rafał Trzaskowski,