Since winning power back from the hands of his populist rivals a year and a half ago, Poland’s Prime Minister Donald Tusk has faced one very stubborn roadblock to his plans: the country’s president.

Poland’s presidential election will determine whether the country can restore the rule of law and remain a reliable partner in the European Union after nearly a decade of divisive right-wing populist rule.

The two main contenders for Poland’s presidential election on Sunday locked horns over Europe and traded personal barbs this week as they each made final bids for the support of floating voters. The winner will take over from current President Andrzej Duda,