The former European Union leader and ex-prime minister Donald Tusk has been elected head of the strongest party in Poland’s fragmented opposition. Tusk, 64, said he was returning to Polish politics and to the opposition Civic Platform party to help fight the “evil” of the current rightwing government. Tusk co-founded Civic Platform, a centre-liberal party, in 2001. It ruled Poland for eight years – most of the time with Tusk as prime minister – before the current conservative team won power in 2015. “I know that many Poles were waiting for this black dream to be over,” Tusk said about the current government of the Law and Justice party that has put Poland on a collision course with the EU. “Today, evil rules in Poland and we are ready to fight against this evil.” The EU and its court have opened procedures against Poland’s current government, saying its changes to the justice system and opposition to some EU decisions, including on relocation of migrants, have gone against the 27-member bloc’s principles. Tusk said his return was dictated by the conviction that Civic Platform was “necessary as the force ... that can win the battle with Law and Justice over Poland’s future”. “There is no chance for victory without the Platform,” Tusk said. He said he also had a sense of responsibility for the party he had founded and led for many years before taking on the position of EU Council head in 2014. The current government of Law and Justice and two small partners continues to lead opinion polls thanks to its generous family bonuses and conservative policies that appeal to the Catholic majority in society. But the pressure of accumulating disputes with the EU and an internal struggle for power and influence have been visibly shaking the unity and loyalty in the coalition, which recently lost its majority in parliament.