Donald Tusk has taken over as leader of Poland’s main opposition party

POLITICAL COMEBACKS are always a gamble. “Can the soufflé rise twice?” was the withering putdown once delivered by Australia’s then treasurer, Paul Keating, to a re-emergent rival. (It turned out that it couldn’t.) For Donald Tusk, a former prime minister of Poland who returned to domestic politics this month after an international career that took him to the presidency of the EU’s Council, the obstacles are formidable. Since coming to power in 2015, the right-wing populist Law and Justice party has put its stamp on Poland’s institutions and found itself at loggerheads with the European Commission, which accuses it of undermining the rule of law. Liberals hope that Mr Tusk’s return as leader of the centrist Civic Platform, the largest opposition party, will help defeat the populists. It will not be easy.

Moderate and pro-European, Mr Tusk has long presented himself as the antithesis of Law and Justice and of Jaroslaw Kaczynski, its veteran leader. In the late 2000s Mr Tusk appealed to Poles by offering what he called a policy of “warm water in the tap”, focusing on gradually raising living standards (with the help of EU funds, of which Poland has been the largest net beneficiary), rather than on grand projects. Civic Platform, which he co-founded in 2001, did well: it ran Poland for eight years from 2007 onwards, with Mr Tusk as prime...