It is not very often that a candidate country admonishes the organization it wants to join. Yet that is the story in Turkey, where President Recep Tayyip Erdogan has gone on a series of tirades against the Netherlands, Germany and the European Union at large ahead of a referendum this weekend on constitutional changes that would grant Erdogan more powers and transform Turkey’s government from a parliamentary to a presidential system. Turkey has been stuck in accession talks with the EU for over a decade.

Erdogan’s anti-EU streak began with attacks early last month against the Netherlands, which he called a “banana republic” and a “Nazi remnant,” while claiming it was somehow responsible for the 1995 Srebrenica massacre. Erdogan was livid at the Dutch government’s decision to ban a political rally by Turkish immigrants in Rotterdam in support of the constitutional referendum. The Hague also denied entry to a plane carrying the Turkish foreign minister to the rally and expelled another Turkish minister who was already in the Netherlands. ...