Poland votes on Sunday in parliamentary elections that could greatly affect future ties with the European Union and neighbouring Ukraine, as the ruling populists bid for a third consecutive term in power. Opinion polls indicate the nationalist Law and Justice (PiS) party will get the most votes but may struggle to build a governing coalition, giving a chance to the opposition led by former EU chief Donald Tusk. Polling stations across the EU and NATO member open at 0500 GMT and close at 1900 GMT, with exit polls expected immediately after and final results on Monday. Some 29 million people are eligible to vote, including half a million registered abroad in a large diaspora. A PiS victory could exacerbate tensions with the EU and Ukraine and will dismay campaigners concerned about the future of media freedoms, women’s and migrants’ rights. “We have ceded some of our powers to the EU but now that’s enough, nothing more. We are in the EU, and we want to stay there, but in an EU of sovereign countries,” PiS leader Jaroslaw Kaczynski said at the party’s last major rally in Sandomierz on Friday. At his own final rally ahead of a day of electoral silence on Saturday, Tusk told supporters in Pruszkow that PiS had “secret plans” to leave the EU and said they were “leading the country down the wrong path”. “This is the most important day in the history of our democracy since 1989,” Tusk said at the rally. “We will also be voting for Poland to remain in the European Union. Poland is the heart of Europe,” he added. PiS has vowed to press ahead with controversial reforms of the judiciary which it says are aimed at rooting out corruption but which the EU sees as undermining democracy. The row has blocked billions of euros in EU funding. The most likely coalition partner for PiS would be Confederation, a far-right party that has called for an end to Poland’s large-scale assistance for Ukraine and has campaigned on a strongly anti-migrant platform. But Confederation has publicly ruled out such an alliance and some analysts say it is unlikely to happen because of simmering tensions between the two parties. The hope among liberals is that, even if Tusk’s Civic Coalition comes second, it will have enough votes to form a government with two smaller potential allies. The elections are for the lower and upper houses of parliament and PiS has organised a referendum on the same day with leading questions on migrants and the economy, which the opposition has called for people to boycott. Supporters of PiS say victory on Sunday will allow the party to fulfil its vision of a strong, sovereign Poland based on traditional Catholic values. The campaign has been characterised by personal attacks on Tusk by the ruling party, which has accused him of working in the interests of Germany, Russia and the EU. PiS has also ramped up anti-migrant rhetoric, with Prime Minister Mateusz Morawiecki saying the country should be protected against illegal immigrants “who have no respect for our culture”.