Voting has started in a knife-edge election in Slovakia that could decide whether the country sticks with its liberal, pro-western line or abandons its staunch support for neighbouring Ukraine to lean more towards Moscow. After a virulent campaign that has included physical brawls and amid a wave of online disinformation, the populist, nationalist three-time prime minister Robert Fico and his Smer-SD party were neck and neck with the newcomers Progressive Slovakia heading into the vote, with PS just ahead in two of the final four opinion polls. However, neither party will come close to a majority in the 150-seat parliament and whichever one finishes first is unlikely to find it easy to form a ruling coalition: the results of half a dozen smaller parties will be critical to the outcome. Hlas-SD – formed as a spin-off from Smer by Peter Pellegrini, who took over as prime minister after Fico was forced to resign in 2018 after mass protests over the murders of an investigative journalist and his fiancee – was third in all polls. The moderate social democratic party could become kingmaker. It has so far kept its options open and refused to say which party it would back, but is widely believed to favour an alliance with Smer over the more socially liberal PS. Fico, 59, has become more strident in opposition, adopting more pro-Russian views at variance with the centre-right coalition that ruled the country after the previous 2020 elections before falling apart last year and being replaced by a caretaker cabinet. He has said he will not send “another bullet” to help defend his country’s eastern neighbour from Russian aggression, labelled western and EU sanctions against Moscow “useless”, and promised to veto any Ukrainian application to join Nato. A vocal admirer of Hungary’s autocratic leader, Viktor Orbán, and to a lesser extent Poland’s national-conservative Law and Justice party, Fico told a rally this week: “War always comes from the west. And freedom and peace always come from the east.” He has also campaigned against immigration and LGBTQ+ rights and – himself the subject of several court inquiries – threatened to sack National Criminal Agency investigators and the special prosecutor dealing with high-level corruption cases. Analysts have said that while during previous mandates Fico proved pragmatic and keen to avoid unnecessary clashes with Brussels or Slovakia’s Nato allies, support from Orbán and potentially other nationalist leaders could embolden him. His policies, however, would depend on what coalition Smer – if it wins – could form. Potential partners range from Hlas to the far-right Republika party, made up of former members of the openly neo-Nazi People’s Party Our Slovakia. More moderate liberal voters, meanwhile, have flocked to PS, led by the 39-year-old Oxford political science graduate and European parliament vice-chair Michal Šimečka, which has said it will not enter government with extremists or Fico. It has run a strongly pro-western campaign, vowing to “deepen European cooperation” and continue to help Ukraine, and is a rare example in conservative, Catholic Slovakia of a political party in favour of LGBTQ+ rights. Popular among young people, PS narrowly missed out on parliamentary seats in the 2020 vote. It has said it is open to working with small conservative parties, though differences on social policy issues such as same-sex marriage could prove an obstacle. Other parties likely to clear the 5% bar to enter parliament include OLaNO, which won the 2020 election, the rightwing We Are Family, the liberal Freedom and Solidarity, the centrist For the People, Republika and the ultranationalist Slovak National party. Polling stations opened at 7am CET (0600 BST) and will close at 10pm, with exit polls expected soon after and final results due on Sunday morning.