Corbyn's positioning on Brexit has come straight out of the Blair playbook – this doesn't feel like principle-driven politics

During the EU referendum two years ago, Jeremy Corbyn refused to share a Remain platform with previous Labour leaders if Tony Blair was present, and the event never happened. Yet his positioning on Brexit since has been right out of the Blair playbook.

Constructive ambiguity served Labour well at last year’s general election. But Corbyn has been on a journey since, nudged along a path to a softer Brexit by Keir Starmer, the shadow Brexit secretary. Corbyn’s Eurosceptic instincts left him out of step with Labour members, many Labour MPs and most trade unions (an important behind-the-scenes influence). Being branded the midwife to Theresa May’s hard Brexit started to hurt.

First, Labour came out in support of a customs union (not the EU’s existing one). Last night Labour called for “full access” to the EU single market, in effect another “a” rather than “the” which, crucially, stops short of full membership of it. Party sources labelled it “the softest possible” Brexit.

The shift is welcome, as a soft Brexit would cushion the economic impact. But it is hard to escape the conclusion that Labour’s policy is driven by expediency as much as principle. Of course, you could say the same about May’s, with gold-plated knobs on.

Although both main parties are split on Brexit, Labour’s divisions get less media attention because they are in opposition. Labour has now put limiting those divisions ahead of defeating the government when the Commons votes next Tuesday on amendments passed by the Lords to the EU (Withdrawal) Bill. They recommend retaining membership of the single market by joining the European Economic Area (EEA), which includes the 28 EU countries plus Norway, Iceland and Liechtenstein. Labour’s shift stops short of backing this; its MPs will probably be ordered to abstain.

Starmer hopes his new policy will limit the number of pro-European Labour MPs who will defy the whip by backing EEA membership. Some 70 were threatening to do so. However, the signs are that there will still be a sizeable revolt. Pro-EU figures are furious that the leadership has not gone further. They insist that it is wrong to describe EEA membership as “the Norway option”, which Corbyn rejects because it would leave the UK as a “rule taker” with no say when the EU makes the rules. The pro-Europeans say Norway would be the starting rather than the end point; the UK would negotiate from a position of strength as the first EU member to join the EEA and because of our economic clout.

In trying to unite Labour MPs, the leadership has made a humiliating defeat for the government less likely. The band of about 20 pro-EU Conservatives might vote for the cross-party Lords amendment on the EEA, now doomed to fail because of Corbyn’s refusal to endorse it. But the Tories will not back the Labour frontbench amendment.

Starmer probably judged there was only a very slim chance of the Lords’ EEA move being approved by MPs, since Labour would have split. Two-thirds of Labour-held constituencies voted Leave in 2016 and several of their MPs would not back EEA membership even if Corbyn did. They do not want to be accused of endorsing the free movement of people – part of the single market package – which Labour accepted would end in its election manifesto last year.

Perhaps Starmer is playing a clever, longer game. Labour’s single market and customs union stance might yet appeal to Tory pro-Europeans when the Commons votes on May’s deal this autumn. That is the critical moment.

It’s a bit rich for the Tories to mock Labour’s latest bit of constructive ambiguity when, two years after the referendum and nine months before we leave the EU, they haven’t even negotiated a Brexit policy with themselves, let alone the EU27. But to have credibility, an opposition does need to answer the “what would you do?” question.

In the unlikely event that we have an election and Labour takes over the negotiations, the frosty atmosphere would certainly improve. Rubbing out May’s red lines would open up a new game. But only up to a point. Labour’s new policy is still a variation of the Tories’ “have cake and eat it” approach. Would Brussels really allow a Labour government to “retain the benefits of the internal market” as the party seeks, without accepting its obligations? I doubt it.

Corbyn would get a better deal if he went down the EEA route. His caution about the Labour Leave vote in the North and Midlands is understandable. But it may be softening. A YouGov survey of 23,000 people suggests that one million Labour voters who backed Brexit are now having second thoughts. Writing in Prospect, the former YouGov president Peter Kellner concludes that the 2-1 backing for Remain among Labour supporters in 2016 is now almost 3-1. Corbyn has more room for manoeuvre than he thinks; he should use it.