Federalists are pinning their hopes on Ursula von der Leyen, the probable next president of the European Commission, to take major steps towards their dream of a United States of Europe.

Mrs von der Leyen, a German defence minister, has said she wants her grandchildren to grow up in a federal Europe run along the lines of the US or Switzerland and called for an EU army.

“It is very important to have a president of the European Commission that has identified herself as a federalist," Mr Gozi, president of the Union of European Federalists, said.

“She has spoken clearly, openly and with courage, as it is not fashionable anymore to speak of a United States of Europe,” he said, “to have the courage of using certain words can mean having the courage to do certain actions.”

“We certainly knows she wants defence integration,” Christoph Glück, president of the Young European Federalists, said, “She agrees on the ultimate goal of a United States of Europe.”

“It is unclear whether she sees this a decision for the next 50 years, if she wants to wait and see for public support to build up or if she thinks more integration now is the way to tackle the challenges facing the EU,” Mr Glück said.