The U.K.'s departure, due on March 29, is likely to be delayed as U.K. lawmakers wrangle over whether to approve a withdrawal agreement with the bloc. Parliament voted this week to seek a delay of at least three months.
A group of largely older protesters set out along a muddy coastal path from Sunderland, 270 miles (435 kilometers) north of London, shouting "Accept democracy" and "Rule Britannia." They plan to arrive at Parliament on March 29, though they are not covering the whole distance on foot.
Former U.K. Independence Party leader Nigel Farage, who joined marchers Saturday, said that "if politicians think they can walk all over us, we're going to march back and tell them they can't."
A senior European Union official is floating the possibility of a two-step delay to Britain's departure from the bloc, currently scheduled for March 29.
Britain is expected to seek a short delay if lawmakers finally pass a twice-rejected EU withdrawal deal, or a longer one if they don't.
European Commission Vice President Frans Timmermans told Germany's Funke newspaper group in comments published Saturday that Britain must know why it needs a delay. He added that "as long as this isn't clear, Brexit can only be delayed for a few weeks, solely to avoid a chaotic withdrawal March 29."
Timmermans said: "During this time, the British must tell us what they want: new elections? A new referendum? Only after that can we talk about a several-month extension."