For the past 18 months, Poland has been one of Ukraine’s closest allies. Those ties have frayed ahead of Sunday’s Polish elections, where the ruling populist Law and Justice (PiS) party is currently ahead in the polls. It’s a worry for the European Union, after pro-Russia parties won recent elections in Slovakia. In September the Polish government joined an embargo on Ukrainian grain imports in response to protests from its farmers in rural strongholds, prompting Ukraine to appeal to the World Trade Organisation. A public row followed, as Zelensky criticised “certain” countries for “playing solidarity politics” while Polish President Andrzej Duda compared Ukraine to a drowning person who can “drag you down”. The PiS is also running on an anti-migrant platform. The majority of Poles remain pro-EU and pro-Nato, identifying Russia as a threat. But if the PiS wins and creates a right-wing coalition, it will threaten Poland’s relationship with both the EU and Ukraine – possibly permanently. The main beneficiary will be Russia.