WITH just 47 days, a scarcity of hours, tens of minutes and a clutch of seconds to go till Britain leaves the European Union, let’s perform a thought experiment. Bracket your political animus to the parties involved. Suspend your disbelief. Can any of you outline the Labour Party’s principal objections to Theresa May’s deal in 280 characters or fewer? Take your time now. It’s not as if we’re in any kind of rush.

Struggling? Okay. Let’s trim back our ambitions. Instead, try to identify just one coherent objection to the Prime Minister’s European accord which you’ve heard from camp Corbyn. Here, a few wisps of slogan might swim up from the dark banks of your unconscious. You may remember something about the customs union. You might hear the phrase “a jobs-first Brexit”. If you can make heads or tails of what that nifty bit of rhetoric actually means in practice, I salute you.

But when you peel back the party politics and the awkward Commons calculus facing Theresa May’s minority government, when you reckon with what Jeremy Corbyn and his leadership team have said about Brexit, the basis of their opposition to the PM’s withdrawal agreement is impossible to state clearly.

We’ve reached a fork in the road and Labour – more than any other political party – finds itself birling at the crossroads. The Tory ructions about where we go from here are noisier, certainly, but the incoherence and the evasions of the Labour leadership have reached a terminal phase.

Through the dying days of the Brexit process, with all the options still notionally on the table, Labour has maintained an uneasy truce between die-hard Remainers who do not wish to leave the EU and people inclined to leave the EU in the least-worst terms achievable. Constructive ambiguity is a grand way of holding together any broad political coalition in ordinary times – but ambiguity ceases to be constructive when the alternatives are directly irreconcilable.

With just over a month on the clock, Labour’s internal truce can hold no longer. It is beyond time to untangle the fankle of where Labour stand. So, what’s the priority? Is it stymieing Brexit or achieving it in the most orderly, least damaging way possible? Choose.

One of the characteristics of the late-stage Brexit debate is that considerable time and energy has gone into driving up blind alleys. The insidious fiction that “no deal” can somehow be ruled out has attracted more sympathy than it merits.

In the absence of a deal which can command a majority in the Commons, Article 50 automatically bites. Adiós. Auf Wiedersehen. Goodbye. What’s needed is a positive alternative. And as things stand, the only alternative is the EU withdrawal agreement May struck on November 25.

In March 2017, the silver-quiffed former prosecutor Keir Starmer sketched out Labour’s “six tests” against which any Brexit deal would be tested. “Does it ensure a strong and collaborative future relationship with the EU?” Not to be outdone by the Tory star-pony club, Starmer’s second test was that the Brexit accord must “deliver the exact same benefits as we currently have as members of the single market and customs union”.

Brexit should “ensure the fair management of migration in the interests of the economy and communities”, he said, “defend rights and protections and prevent a race to the bottom”, protect “national security and our capacity to tackle cross-border crime”. Lastly, Sir Keir insisted the deal must “deliver for all regions and nations of the UK”.

Like the concept of “fair management”, “to deliver” is one of those Blairite euphemisms which gestures towards down-and-dirty practical mindedness, but which means nothing and commits you to nothing. A combination, then, of the unachievable, the indecipherable and the unobjectionable.

This week, Jeremy Corbyn’s team have dreamt up five more tests in a letter to the Prime Minister. Calling on Theresa May to modulate her “negotiating red lines”, Starmer is now seeking a “permanent and comprehensive UK-wide customs union”, “close alignment with the single market,” “dynamic alignment of rights and protections” and a concordat on security co-operation. But here’s the kicker. Corbyn’s letter concludes “we believe these negotiating objectives need to be enshrined in law before the UK leaves the EU to provide certainty for businesses and a clear framework for our future relationship”.

This is amazing piffle. Labour politicians have a guilty habit of basic constitutional illiteracy. You may well remember when Gordon Brown suggested to the Scottish electorate that Holyrood could be constitutionally entrenched as “permanent, irreversible and indissolvable” without touching the principle of UK parliamentary sovereignty, which says Westminster can make or unmake any law whatsoever.

The Fixed-term Parliaments Act was meant to enshrine the electoral calendar in law. The Scotland Act 2016 supposedly gave Holyrood permanent constitutional ballast and security from invasions of its prerogatives by Westminster. As the Supreme Court made vividly clear across a string of recent cases, these restrictions are meretricious twaddle, with no constitutional force to them whatever.

Without ripping up the basic rules of the British state, there is no power in the land capable of entrenching these negotiating positions or the employment rights guaranteed in EU law. We have, to borrow a phrase, “taken back control” of these regulations. Whip together a parliamentary majority, get it through the Lords, activate the Queen, and any of these rights and protections can be stripped from the statute book. Their survival is – and will always be – politically contingent. Keir Starmer must remember enough of Public Law 1 from his undergrad days to know this is a non-starter.

It is difficult to see the diehard unionist case against Theresa May’s deal having much authentic traction inside the Labour Party either. Taking their cue from the DUP, most Tory refusiks have taken up Arlene Foster’s argument that the backstop will “separate” Northern Ireland. Geographically, you might well think the existence of the Irish Sea represents a longer-standing threat to the integrity of the United Kingdom, but ho hum. It’s seemingly the borders of the mind which matter to the DUP, and the party’s mind seems capable of remarkable flexibility.

When it comes to abortion and the gays, Northern Ireland’s separateness is a feature, not a bug. When George Osborne passed the Northern Irish Assembly the power to levy its own rate of corporation tax back in 2015 to facilitate greater alignment with the cut-rate regime south of the border, I don’t remember Arlene and Nigel and Sammy doing their collective dingers.

For all of Scottish Labour’s unionist puffery in recent years, it is difficult to believe many of its MPs would toss and turn in their bunks if the backstop contingency kicked in. Which leaves you with my opening question: what, precisely, do pro-Brexit Labour politicians really object to in Theresa May’s deal, beyond their own line of impossibilist fantasies and constitutional impossibilities?

This week, the SNP has been getting its retaliation in first. Mike Russell attacked the Labour leader, saying that “if Jeremy Corbyn enables a Tory Brexit his party would have to take responsibility for massive damage to Scotland”.

The SNP have consistently maintained that a choice between May’s deal and crashing out of the EU without a deal in place is a false choice. They were right. It was a false choice. But as the clock winds painfully down through February, it will soon cease to be, unhappy as that is, unnecessary as that is. “Deal, or no deal?” The reality confronting Ian Blackford and Jeremy Corbyn looks increasingly binary.