BRUSSELS — Just a few years ago, the European Union faced down a populist Greek government whose debts threatened the common currency, the euro, and the very integrity of the bloc.

But if the European Union thought the problem was behind it, it is now back — and bigger and more dangerous than ever — in Italy, whose populist government is also insisting on breaching bloc rules for fiscal discipline in order to keep faith with its voters.

The European Union rejected Italy’s draft 2019 budget this week and demanded revisions; Italian leaders, like the Greeks before them, say that they will ignore those demands.

This clash between an elected government that ran on increasing public spending and the technocrats of Brussels encapsulates the dilemma at the heart of the European Union — its democratic deficit as it tries to manage a currency shared by differing sovereign states without a common budget or finance minister.