Donald Tusk returned to power in Poland to great anticipation at home and among European Union allies a little over 18 months ago. Now another awkward cohabitation between the prime minister and head of state threatens to create more obstacles for his struggling government.

Karol Nawrocki, the nationalist outsider who scored a shock victory in June’s runoff for president, will be inaugurated on Wednesday, setting up a battle with Tusk’s pro-EU administration. Instead of securing a long-awaited ally, the government is now preparing for an opponent in the presidential palace again.

Backed by the Law & Justice party that Tusk ousted from government, Nawrocki is expected to wield his ability to block legislation. While the role of president is largely ceremonial, Tusk’s coalition doesn’t have a big enough majority in parliament to overturn a veto on issues such as abortion rights and measures to tackle the budget deficit.