Croatia is voting Wednesday in a parliamentary election after a campaign that centered on a bitter rivalry between the country’s president and prime minister. The ballot pits the ruling conservative Croatian Democratic Union, or HDZ, led by Prime Minister Andrej Plenkovic, against an alliance of centrist and left-wing parties informally led by populist President Zoran Milanovic and his Social Democratic Party, or SDP. The election is being held as Croatia, a European Union and NATO member, struggles with the highest inflation rate in the eurozone, a labor shortage, illegal migration and reports of widespread corruption. At stake in the race for Croatia’s 151-seat parliament isn’t just the Adriatic Sea country’s future domestic policies, but also the EU’s unity as it grapples with the instability from Russia’s full-scale invasion of Ukraine. If the HDZ stays in power, the country would continue on a pro-Western course in supporting Ukraine in its fight against Russia. Success for SDP could put it on track for victory in the European Parliament election in June and the presidential election in December. It would shake the HDZ’s long dominance of politics and potentially open space for stronger pro-Russia influence in the country, akin to Hungary and Slovakia. Polls close Wednesday evening and official results are expected Thursday. Most pre-election polls predicted a HDZ victory, but without enough seats to rule alone. The left-wing opposition may benefit from discontent with the country’s high inflation and the general economic malaise in most EU member states. Smaller parties on the right and the left could be key to both the HDZ and SDP in their quest for power. The HDZ has largely held office since Croatia gained independence from the former Yugoslavia in 1991. The Balkan nation became the newest member of in 2013, and joined Europe’s passport-free travel area and the eurozone last year. The president holds a largely ceremonial role in Croatia, while the prime minister exerts most of the political power. The election has played out as the final episode in the long-running rivalry between Plenkovic and Milanovic. After Milanovic scheduled the election and announced his surprise bid for prime minister, he began campaigning on behalf of the SDP. But Croatia’s constitutional court judges stepped in, saying the move was unconstitutional. The judges said that the president can’t run for prime minister, take part in the parliamentary election or campaign in favor of any party,. Milanovic refused, openly ignoring the top court and continuing to campaign in favor of the left-wing alliance. “I hope that the citizens will vote for a Croatia that respects the constitution and the constitutional order, for a Croatia that belongs to the Western and transatlantic democratic circle,” Plenkovic said after he cast his ballot, appearing to reference Milanovic and his alleged breach of the constitution by actively taking part in the election process. Milanovic said that with his statement, Plenkovic breached electoral silence on the vote day. “You have a prime minister who even today did not resist breaking that symbolic election silence, going wild and talking nonsense about violating the constitution, respecting the law,” the president said. Milanovic also accused Plenkovic and the HDZ of rampant corruption and “massive theft” of state funds, referring to past and present scandals, some of which had ended up in the courts. Plenkovic, who has led the government since 2016, repeatedly denied the accusations, saying Milanovic as the prime minister would shift the country away from the EU and NATO. Milanovic has often voiced a pro-Russia stance during the war in Ukraine, opposing the training of Ukrainian soldiers in Croatia as well as sending weapons to Ukraine because, in his view, it only prolongs the war. He also criticized the EU’s policies over Ukraine.