LONDON • The opposition Labour Party wants Britain to stay in the European Union's single market for an extended period after it leaves the bloc, a shift in its position that could undermine Prime Minister Theresa May's efforts to deliver her vision of Brexit.
The proposal, which would mean no additional Customs or migration controls in March 2019, would allow more time to finalise details of Britain's departure, and give government and business time to prepare, said Labour's Brexit spokesman Keir Starmer. It would also eliminate the need to negotiate a transitional arrangement at the same time as a final deal.
"There would be no need to set up complex alternative Customs or trading relations," Mr Starmer wrote in the Observer newspaper yesterday.
"It is a grown-up acknowledgment that bespoke transitional arrangements are highly unlikely to be negotiated, agreed and established in the next 18 months."
If Labour can force a parliamentary vote in support of its position, it will put pressure on Conservative lawmakers who oppose leaving the single market to fall in behind it. Legislation that seeks to prepare Britain for leaving the EU returns next month to Parliament, where Mrs May does not have a majority, and lawmakers are expected to battle over amendments.
Mr Starmer was clear that Labour remains committed to implementing Brexit. He also said his party wanted to see a final settlement that allowed Britain "more effective management of migration" - something that would make permanent membership of the single market difficult. And he emphasised that he saw the transition as time-limited.
"It cannot become a kind of never-ending purgatory," he said.
Instead, he said Labour remained open to "negotiating a new single market relationship" or "working up from a bespoke trade deal".
Some Labour lawmakers are pressing for more. A new group, Labour Campaign For The Single Market, will be unveiled tomorrow, pushing to get the party policy changed to supporting continued single-market membership.
Business leaders overwhelmingly support continued membership, while several prominent Conservative lawmakers have defied Mrs May to speak publicly of their support for ongoing single-market membership.
"Labour is now the party of soft Brexit," said Mr Mujtaba Rahman, an analyst at Eurasia Group.
"May would have a huge dilemma if a majority of MPs were to back Labour's policy. If she accepted a Commons vote in favour of it, she would face a backlash from hardline Brexiteer Tory MPs, who might well try to oust her by forcing a Tory leadership contest."
The shift in Labour's policy comes as Britain prepares for another round of negotiations in Brussels today, which EU officials have signalled are unlikely to yield much progress.