Michel Barnier, the European Union’s chief Brexit negotiator, warned on Tuesday that Britain’s seeming inability to decide on an orderly departure agreement has made a so-called no-deal Brexit more likely with less than two weeks until April 12, the latest deadline.

While a further extension of the deadline was possible, nothing was certain. Here’s what could happen if Britain leaves the bloc without a deal.

Ports could be jammed.

Ferries and trains zip back and forth between southeast England and Calais in France carrying food, goods and people between Britain and the rest of the European Union. If Britain leaves without a divorce agreement, many worry that issues with new customs arrangements could lead to miles of traffic jams, forcing trucks to sit for hours on highways as food rots and manufacturing processes grind to a halt.

“I expect to see long queues at the ports because traders, importers and exporters and the logistics supply chain are not prepared for the new customs arrangements here or in the E.U.,” said Duncan Buchanan, the policy director at Britain’s Road Haulage Association. “We will get a massive slowdown in the supply chain.”