The prospect of Marine Le Pen's far-right National Rally (RN) forming a government in Paris after President Emmanuel Macron called a snap election has changed everything. It has sent a shudder through the EU's bureaucracy in Brussels and in Frankfurt, the seat of the European Central Bank officials have told POLITICO.

After all, it's one thing to let off a pro-EU, statesmanlike leader for the type of reckless spending that endangers the economic stability of the eurozone. It's quite another if it's carried out brazenly by a nationalist firebrand who doesn't think the rules are worth the paper they're written on in the first place.