French voters elected as president Emmanuel Macron, whose platform espouses a stronger EU and a tough line in negotiations on Britain's exit from the bloc. Perhaps just as important, they rejected far-right contender Marine Le Pen, whose EU bashing knows few bounds.
But if champagne corks are popping in Brussels, beware of the hangover: Brexit negotiations could go horribly wrong. Italian elections could see an anti-euro movement become the biggest party. Greek finances could wreck the value of the shared European currency.
Despite overwhelming support for Macron across the continent, the new French leader remains a political novice, untried and untested on European issues. And even as he celebrates European unity, he has argued that the bloc needs a fundamental retooling.
"It makes it tough to predict how he will act — in France and also in the EU," said Hendrik Vos, a European policy analyst at Ghent University in Belgium.
For a dozen years, the European Union has slumped from one crisis to another, from referendum losses to bailout emergencies, a situation so dire that the term "muddling through" has taken on a ring of deliverance instead of setback.
Last year was particularly bad, with Britain's vote to leave the bloc on June 23 producing the most cathartic day in the EU's 60 years. Suddenly, the ever-expanding union started to shrink. The election in the United States of President Donald Trump created even more panic, especially after he showed such delight at Brexit and potential further breakaways that the EU threatened it would "promote the independence of Ohio and Austin, Texas" if he didn't stop.
2017 looked set to be even worse for the union, with firebrand Geert Wilders leading the Dutch polls for March elections and Le Pen rising in France, both thriving on their hatred for anything even remotely linked to the EU. After Trump's election proved unpredictability was the norm, anything could happen.
But Wilders disappointed in the Dutch polls, and Le Pen fell short Sunday. The German elections are up next, in September, and both Chancellor Angela Merkel and Socialist challenger Martin Schulz have impeccable pro-EU credentials.
Little wonder there are some shoots of optimism this spring.
Macron campaigned for the European Union at a time when it was fashionable and politically expedient to dump on it. Now he has to deliver on his words.
Key will be his relationship with the German leader. Germany and France have been the twin engine driving the European Union as it grew from six members to 28. Former world war enemies, they stuck together as much of the continent gelled around their drive for unity. Le Pen saw Germany much more as a competitor and a meddler in French affairs, another reason why her presidency would have spelled doom for the EU.
The relationship unraveled under President Francois Hollande. It was not so much that Hollande was a Socialist and Merkel a Christian Democrat — after all, Francois Mitterrand and Helmut Kohl had a political bromance for the ages. It was because Hollande seemed as weak on the European stage as he was at home.
Macron realizes he will need to do better and has set out to make Berlin his first port of call. But like Hollande, he will need to establish himself at home before becoming an effective champion of a closely knit Europe.
"To have a voice of authority in Europe, it is important to be credible and run your own country smoothly," Vos said. "That is a tough chore for Macron."