After a choppy few years, they had a precious opportunity to show unity as they huddled to make appointments for prestigious EU jobs , people who will run the world's biggest trading bloc over the next five years.
Instead, leaders bickered, pointed fingers, organized unsuccessful backroom meetings to stake out narrow nationalist agendas and sought first and foremost to protect their own party political interests.
"Our credibility is fundamentally stained by all these too-long meetings," French President Emmanuel Macron said after an all-night summit fell apart without agreement on the top posts. "We are a club of 28 that meets without ever deciding anything. Our compatriots see it," he said, arguing for fundamental change to how the EU works .
German Chancellor Angela Merkel had little positive to say about what happened. "Today people find this pretty bad. I can believe that and we'll have to live with it." To make matters worse, the leaders had already failed to agree on the top jobs at a two-day summit less than two weeks ago.
They will try yet again Tuesday. Instead of highlighting a united "Team Europe," to use Macron's phrasing, EU leaders indulged in the kind of backroom horse trading for Brussels jobs that has long raised the ire of anti-EU populists who claim the bloc is opaque and out of touch with the continent's 500 million people, who need answers to much more urgent questions.
EU voters turned out in numbers not seen in two decades for European Parliament elections in May, showing a renewed interest in the bloc's future after years marked by battles over Brexit and the continent's migrant crisis.
"No other major democracy in the world has such a bizarre and arcane method for choosing its political leadership," Dutch EU lawmaker Sophie in 't Veld tweeted Monday. "Over 200 million people have voted (for European Parliament), but 28 individuals withdraw behind closed doors and play musical chairs."
The challenge at Sunday's summit seemed straightforward enough. EU Commission President Jean-Claude Juncker and Council chief Donald Tusk are both closing in on the end of their mandates this autumn, as is foreign policy chief Federica Mogherini. European Parliament President Antonio Tajani is due to be replaced on Wednesday in a vote by lawmakers that would not require the leaders' consent.
All are high-profile jobs involving meeting and negotiating with world leaders like U.S. President Donald Trump and China's Xi Jinping. Or fighting for trade deals with economic heavyweights like Japan, or defending strategic agreements with Iran.
After the failed June 20-21 summit, drawn-out talks to carve up the jobs resumed among a small group of leaders at the Group of 20 meeting of leaders in Osaka last week, before continuing Sunday at a summit of all 28 EU leaders in Brussels. The leaders haggled into the night and continued as a pastel pink sunrise faded into Monday morning. By the time the leaders threw in the towel, the midday sun was beating down on EU headquarters.
Pledges of increased electoral accountability on how the EU leadership is picked soon faded. While May's EU elections attracted more voters to the ballot boxes across the continent, they also delivered a more splintered parliament, in which the two biggest groups cannot command a majority for the first time.
That means that divisions between political groupings have only deepened, making it harder than ever to balance political, geographic and gender considerations when assigning top jobs. Dutch socialist Frans Timmermans hoped to replace Juncker as president of the EU's Commission, even though the S&D socialists group in parliament is smaller than the EPP Christian Democrats. The appointments have to be signed off by European lawmakers and that may not be so easy in the new Parliament.
Timmermans wasn't invited to the summit, but squeezed in a meeting with one of the leaders anyway. A vocal proponent of transparency at the EU, he was livestreamed talking Sunday night with Bulgarian Prime Minister Boyko Borissov at a Bulgarian diplomatic residence discussing his candidature and the Bulgarian's wish list.
But after a few minutes of talking to Borissov, Timmermans pointed to the camera and said: "I'm not sure we should be recording all of this." Immediately afterward, the video clip ended. As the all-nighter dragged on, exhaustion set in and Tusk told the leaders to go home and try again on Tuesday.
"It's complicated and I don't know if we'll get it done tomorrow," said Dutch Prime Minister Mark Rutte. "I'm sure there will be phone calls, but I'm going to let the others have a nap, too," he said.
Lorne Cook, Geir Moulson from Frankfurt, Angela Charlton from Paris and Veselin Toshkov from Sofia contributed.