Europe’s latest presidential election appears to have delivered not a statesman but a slogan – “Poland first” – and with it, a rebuke to the centrist prime minister, Donald Tusk. Poland’s new head of state will be Karol Nawrocki, a conservative historian endorsed by Donald Trump. Mr Nawrocki’s improbable rise – from relative obscurity to the presidency – signals the unfortunate entrenchment of nationalist grievance in Polish politics. He now stands poised to paralyse Mr Tusk’s agenda and perhaps derail Polish access to European funds – using his presidential power of veto to block government legislation or simply relying on...