LONDON — It was another of those make-or-break moments for a Brexit deal that ended in a fizzle. British Prime Minister Boris Johnson traveled to Brussels on Wednesday night for a dinner meeting with European Commission President Ursula von der Leyen, a tête-à-tête the British media dubbed Johnson's "date with destiny." The two talked, but no breakthrough was made.

Some were fearful the dinner date could be a “Last Supper” before all hope of a post-Brexit trade and security deal crumbles. But the two sides agreed to send their representatives back to the negotiating table one last time. Britain leaves the European Union in 22 days.

After dinner, von der Leyen said, “We had a lively and interesting discussion on the state of play across the list of outstanding issues. We gained a clear understanding of each other’s positions. They remain far apart.”

The European Commission president said in a statement that the two leaders agreed that their negotiating teams “should immediately reconvene to try to resolve these essential issues.”

Johnson left without speaking with reporters. “Very large gaps remain between the two sides and it is still unclear whether these can be bridged,” Downing Street said in a statement, adding that the prime minister “does not want to leave any route to a possible deal untested.”

Johnson and von der Leyen agreed that by Sunday a firm decision should be made about the future of the talks.

And so the British prime minister and European Commission president did not forge a future relationship based on a bilateral pact. But they had a nice meal. Fish was on the menu — scallops and turbot — and fishing rights at the top of the talks.

Before Johnson left for Brussels, there was much huffing and puffing in London and Brussels over the last-ditch mission, just three weeks before Britain’s 11-month transition period expires at the end of the month.

The dinner between the two leaders was designed to reset the dynamics and unlock further discussions. Others suspected it could also help either side get an edge on the inevitable blame game that will ensue if Britain ends up crashing out without a deal after four decades in the world’s richest trading club.

Tim Bale, a politics professor at Queen Mary University of London, said, “If they are going to get a deal, it’s best for both sides if it looks as if it was tough negotiating but they pulled off a miracle at the last minute.”

Bale cautioned, “By all accounts, they were quite a long way apart, even on most basic issues, even a few days ago.” He handicapped the possibility for an eventual deal at 50-50.

Both sides insist that an abrupt — and possibly chaotic — departure remains a real possibility.

The “Supper Summit” pitted the devil-may-care Johnson against a frugal and precise former German defense minister who became the head of the European Union’s executive branch a year ago.

The two leaders share some basic traits. Like Johnson, von der Leyen spent some of her formative years in Brussels as the child of a senior diplomat. They went to the same Brussels high school for the children of European bureaucrats, though they did not overlap. Like Johnson, she is the parent of a large brood: seven children in her case, six or more — the precise number is uncertain — in his.

But Johnson likes to bluster his way past the facts, and von der Leyen likes to muster them. He likes to live large — big Italian red wines and weekends at Chequers, the prime minister’s official countryside estate. She arranged for a tiny apartment to be constructed inside the sprawling European Commission headquarters so she could skip the commute to work.

“You run a tight ship,” Johnson told von der Leyen on Wednesday as they entered their meeting, after he sought to take off his mask without keeping a pandemic-friendly distance from her. She politely corrected him, allowed masks off for a moment for the photographers, then told him to put it back on as they again drew close.

The dinner menu was rich with symbolism: French and British fishermen have clashed in the English Channel over scallops, with access to British fishing waters a major point of contention in the talks.

Earlier in the day, when Johnson was still in London, he complained to Parliament about the E.U.’s demands.

“If they pass a new law in the future with which we in this country don’t comply . . . they want the automatic right to punish us and to retaliate,” he said. “And secondly, they are saying that the U.K. should be the only country in the world not to have sovereign control over its fishing waters.”

These are not terms that “any prime minister of this country should accept,” he said.

Britain wants to be able to “take back control” of its sovereignty — for many Brexiteers, that was the whole point of leaving the bloc.

But Europe appears in little mood for compromise.

The disagreements have touched on areas that have been sore points for years — in some cases, centuries.

Belgium’s Flemish fishermen have declared that they have eternal fishing rights in British waters because of a 1666 charter granted by King Charles II to the citizens of Bruges.

“We believe the privilege to still be valid today,” said Flemish Economy Minister Hilde Crevits.

The E.U. also doesn’t want Britain undercutting it on issues such as state aid or environmental regulations to gain a competitive advantage. It wants to make sure British rules stay closely aligned with E.U. ones as a prerequisite for Britain to get relatively unfettered access to the European market.

If a deal isn’t struck, Britain’s exit could be messy and costly. Its trading relationship with its biggest trading partner would default to World Trade Organization rules, meaning overnight tariffs and quotas that would hit both sides, clogging ports and supply chains.

Time is in short supply. A stripped-down trade deal could be approved by leaders and the European Parliament alone, easing passage by Dec. 31. But if there is a more complicated bargain, some national parliaments also would have to ratify it, increasing the possibility of a misstep that leads to Britain’s dropping out of the European market on Dec. 31 without a safety net.

Birnbaum reported from Riga, Latvia. Quentin Ariès in Brussels contributed to this report.