Conservative Karol Nawrocki was inaugurated Wednesday as Poland ’s new president, which could set the country on a more nationalist course and cast doubt on the viability of the centrist government of Prime Minister Donald Tusk.

Nawrocki took the presidential oath in a ceremony in the Polish parliament. The election victory of Nawrocki, who was backed by the nationalist opposition party Law and Justice (PiS), dealt a blow to Prime Minister Donald Tusk’s hopes of cementing the pro-European Union course he has set for the bloc’s largest eastern member and left his government floundering in the polls.

Conservative Karol Nawrocki was inaugurated Wednesday as Poland's new president, which could set the country on a more nationalist course and cast doubt on the viability of the centrist government of Prime Minister Donald Tusk.