BRUSSELS, Belgium (AP) — British Prime Minister Boris Johnson flew to Brussels yesterday for a dinner with the head of the European Union executive that could pave the way to a post-Brexit trade deal — or tip the two sides toward a chaotic economic rupture at the end of the month.

Johnson was welcomed at the bloc’s headquarters by European Commission President Ursula von der Leyen, who gently prompted the British leader to put his face mask back on after a photo call.

The two leaders hope to inject political momentum into trade talks that have become hopelessly deadlocked on key aspects of the future relationship. But Britain and the EU gave ominously opposing views of the main sticking points — and each insisted the other must move to reach agreement.

“A good deal is still there to be done,” Johnson insisted. But he told lawmakers in the House of Commons that the bloc’s demands that the UK continue to adhere to its standards or face retaliation were not “terms that any prime minister of this country should accept”.

German Chancellor Angela Merkel said “there is still the chance of an agreement”, but stressed that the EU would not compromise on its core principles. Merkel told the German Parliament that the bloc would “take a path without an… agreement if there are conditions from the British side that we can’t accept”.

The UK left the EU on January 31 after 47 years of membership, but remains within the bloc’s tariff-free single market and customs union until the end of the year. Reaching a trade deal by then would ensure there are no tariffs or quotas on trade in goods on January 1, although there would still be new costs and red tape for businesses.

When Johnson was crossing over the English Channel to Brussels, down below the impact of Brexit was already visible with extra-long tailbacks in France’s Calais, where truckers were trying to meet the demands of UK companies which want to lay in extra stock ahead of potential disruption on January 1.

“For about the last three weeks we’ve seen an increase in the flow of traffic toward Great Britain due to stockpiling. The platforms, whether it’s the port and the (Euro) tunnel, don’t have capacity to absorb this increase in traffic,” said Sebastien Rivera, secretary general of France’s National Federation of Road Transport.

“Right now, it takes [truckers] easily three or four more hours to cross the English Channel. So it is easily 240 or 300 euros of financial costs to the company, that’s for nothing more than the additional time it takes,” Rivera told The Associated Press.

Failure to secure a trade deal would cause much greater disruption, bringing tariffs and other barriers that would hurt both sides, although most economists think the British economy would take a greater hit because the UK does almost half of its trade with the bloc.

Months of trade talks have failed to bridge the gaps on three issues — fishing rights, fair-competition rules and the governance of future disputes.

While both sides want a deal, they have fundamentally different views of what it entails. The EU fears Britain will slash social and environmental standards and pump state money into UK industries, becoming a low-regulation economic rival on the bloc’s doorstep — hence the demand for strict, “level playing field” guarantees in exchange for access to its markets.

Merkel said “the integrity of the single market must be preserved”.

“We must have a level playing field not just for today, but we must have one for tomorrow or the day after, and to do this we must have agreements on how one can react if the other changes their legal situation,” Merkel said.

The UK Government sees Brexit as about sovereignty and “taking back control” of the country’s laws, borders and waters. It claims the EU is making demands it has not placed on other non-EU countries and is trying to bind Britain to the bloc’s rules indefinitely.