Italy’s new populist government signals a major challenge to the European status quo, but not in the way most observers initially expected. The governing coalition has put its challenge to euro policy on hold. Instead it is turning to a subject on which the European establishment is more vulnerable: migration. The force behind the shift is Matteo Salvini, Italy’s new minister of the interior. He is also the leader of the League, the smaller and more right-wing of Italy’s two ruling parties.
Mr. Salvini shocked Brussels last...