The shadow Brexit secretary will use his visit to urge both EU and UK negotiators to take decisive action to end the impasse ahead of a European Council Summit at the end of the week.
But the frontbencher has also issued a veiled warning to warring factions in his own party, saying they risk losing the public’s confidence if they focus on process and not “the root causes” of Brexit.
Speaking in Brussels, he argued that withdrawal negotiations had become bogged down in “day-to-day technicalities” and were overlooking the big questions that led to the 2016 referendum shock.
He said: “The prime minister is simply trying to survive each week and avoid defeat in parliament. There is no vision for Britain’s future and no plan to tackle the root causes of the referendum result, not least the deep inequalities within our country.
“There is now a real danger that this continued deadlock will fuel public anxiety and alienation.
“Progressives and socialists across Europe should all be concerned about this. It mirrors the rise of right-wing and authoritarian parties across the western world.”
The EU summit starting on Thursday will probably have a heavy focus on immigration with the issue thrust back to the forefront of European politics following the rise of the far-right in several countries.
Most notably, Italy’s new populist government has pledged to deport hundreds of thousands of migrants from the country.
The right-wing League party, which formed a coalition government with the Five Star Movement is the driving force behind anti-immigrant rhetoric and a pledge to deport as many as 500,000 illegal migrants.
Meanwhile, Italy’s home affairs minister has said he hopes to conduct a census of Roma people with an aim of eventually settling the “Roma problem”.
Sir Keir’s call for socialists and progressives to work together will also be interpreted as a call for unity in his own party after a bruising battle over the leadership’s approach to Brexit.
More than 70 MPs defied Jeremy Corbyn’s will and backed a plan in a Commons vote to stay in the EU’s single market after Brexit, with a handful of junior ministers also resigning over the issue.
Sir Keir said: “If in two years all we have done is talk about the process of Brexit rather than the root causes of Brexit, the public – whether they voted Remain or Leave – will not thank us.
“We need a new approach. For Labour, there are two pillars to Brexit. First, negotiating a strong and close future relationship with the EU, underpinned by a customs union and a strong single market deal. Second, a transformational programme for Britain to tackle the deep inequalities exemplified by the referendum vote.”
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