ROME — The campaign before Italy’s national elections on Sunday has been self-obsessed and often petty and unedifying. But it has been instructive about one thing: The political forces that have torn at the global order and the European Union have settled into the mainstream.

Fascists rallied in large numbers in Italian piazzas. The country experienced its worst political violence in years. Formerly unthinkable suggestions, like the mass deportation of migrants, became virtually routine.

The reanimation of Italy’s political ghosts is a worrying harbinger for a European Union already weakened by Britain’s decision to leave the bloc, the electoral setbacks of Chancellor Angela Merkel of Germany, the long shadow of Russia and the rise of an illiberal bloc of nations in the eastern part of the Continent.

In elections in the United States and elsewhere in Europe, the far right had shifted the debate within the political establishment. But in Italy, the birthplace of fascism, they are a full partner in it.