BRUSSELS — No one has ever accused Emmanuel Macron of lacking in audacity. He broke a lot of rules and expectations of deference to become, at 39, the president of France, the closest thing a Western democracy has to a civilian monarch.

Fond of long speeches and cultural references, Mr. Macron has so far not been so good at matching his lofty aspirations with concrete action. Even his vaunted plan to overhaul France’s labor rules has been criticized as too timid.

Undaunted by a sharp loss in popular support in France, or the Pyrrhic victory of Chancellor Angela Merkel in elections in Germany, Mr. Macron took aim this week at another forbidding goal — the reform of the European Union.

In a speech of 100 minutes at the Sorbonne in Paris, against a backdrop of golden stars, Mr. Macron laid out numerous ideas to change what he called “the Europe that we know is too slow, too weak, too ineffective.”