Poland has elected Karol Nawrocki, a conservative historian and staunch nationalist, as its next president in a closely watched vote that signals a resurgence of right-wing populism in the heart of Europe.

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,

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