The government is looking “with interest” at a letter from Jeremy Corbyn setting out terms on which Labour would back a Brexit deal.
Labour demands, outlined in Thursday’s letter, include a permanent customs union with the EU.
Any tie-up between Labour and the Tories might split both parties.
Pro EU Labour MPs such as Owen Smith, former shadow Northern Ireland Secretary, fear the party is abandoning a second referendum and are close to quitting. Yet if the government concedes too much to Mr Corbyn, it will enrage Brexiteer Tories.
All the while, EU insistence that it will not alter the backstop adds to pressure for a Westminster resolution that bypasses unionists.
As Brussels well knows, there is only so far that MPs will allow Northern Ireland to be the stumbling block to a deal with the EU.
The prospects for unionism are not helped by the fact that unionists long ago lost the local Brexit narrative and have struggled to regain it.
DUP leaders repeatedly, and early, made clear that they did not want a hard land border. They were trying to show goodwill, and to dispel any sense that they had a kamikaze approach to Brexit and cross community relations.
Unfortunately that goodwill merely added to the sense that the land border was the over-riding factor relating to Northern Ireland.
The Irish government, indeed almost the entire the Dail, nationalist parties here and the centre parties in NI all promoted that view.
The business community came in behind this stance. The Ulster Farmers Union has faced minimal pressure for its support for the Withdrawal Agreement (WA).
It is baffling that this is so, given that so many unionist farmers backed Brexit. Do they realise that under the WA they will never get a meaningful Brexit, never get the freedom from regulations that they apparently wanted, but will instead get a border in the Irish Sea?
For any unionist Brexiteer, it is the worst of all outcomes.
Yet still there is barely any pressure on the UFU.
London in effect conceded in 2017 that placating nationalist concerns over the land border is its over-riding priority in NI.
Nothing like the same fuss was made over the importance of an unimpeded internal UK single market, which is by far Northern Ireland’s most important economic link.
The spectre of violence has been cited repeated as a reason to oppose any change at all at the land border. Everyone knows, however, that there will be no violence if a border is introduced in the Irish Sea, and so the unstated republican threat has trumped other factors.
Recent developments such as Lord Bew’s essay, in which he pointed out that London had failed to challenge the Irish narrative about Brexit’s threat to the Belfast Agreement, and the possible legal action against the backstop endorsed by Lord Trimble, came late in the day.
The prime minister is almost too far down the road of conceding the nationalist line about the threat to the peace process to retreat. And she does not even seem to be trying.
Mrs May’s speech at Allstate in Belfast this week did not give any detail as to her planned way out of the Brexit impasse, but it was full of praise for the Good Friday accord.
After the prime minister’s speech, when the press was allowed questions, I asked her about Lord Bew’s point that the Irish narrative about the Belfast Agreement had not been challenged. The web version of this article will have a link to the PM’s answer, in which she sidestepped the question – no surprise given that she had just implicitly endorsed the Irish narrative in her preceding speech.
I also asked whether the UK would protect its ultimate right to diverge, in customs and standards, at the land border, and Mrs May didn’t properly answer that either.
Britain to a large extent signed away that right in the WA, which is why republicans are keen on that deal. They pretend they would tolerate it as a substitute to EU membership but in fact realise it would be better than the status quo, because it damages UK sovereignty.
In contrast to such (wholly understandable) opportunism by republicans, genuine EU enthusiasts, such as the Alliance Party, will settle for the WA but would prefer to stay in the EU.
It is not just the tariff/regulatory divergence point on which the UK has been weak, but as my colleague Sam McBride writes on page six, London made a foolish promise to rule out border infrastructure.
One thing above all that they could and should have maintained was a right to use CCTV, to which there is minimal nationalist opposition. Instead, they have in effect let a dissident republican position with tiny support (attacking cameras) dictate the UK Brexit strategy.
In unionism we have contributed to our bad position by barely discussing different types of Brexit and the impacts they might have both on internal cohesion of Northern Ireland and its place in the UK.
Meanwhile, a spectrum of politicians, from Irish ministers to Alliance, settled on a stance not only that there must be no land border checks, but that NI stay in both single market and customs union.
The default unionist position has been to seek the opposite Brexiteer aim of exiting both. Now there is a chance we will leave neither.
The longer I have reported on all the possible forms of Brexit, the more I have thought that the hardest Brexit that is likely to succeed here is Norway, in which the UK (including NI) would stay in single market but leave customs union.
There would be no border at land or sea in terms of regulations because the British Isles would all still be in the single market, which determines standards of goods.
There would, however, be a customs border at land, but Ireland/NI would seek the softest customs border in the world, with CCTV but no permanent checks at the frontier.
Agreeing such a soft customs land border would be tricky but would have been easier to secure if the government and unionists in tandem had pushed for such a softer Brexit from the start.
Instead, Parliament might now endorse the UK staying in the customs union and single market, which would make Brexit a joke, because the UK would be fully in EU trade zone without a say.
It would make a future eurosceptic public rebellion in Britain likely.
One route to a ‘pure’ Brexit is a general election that becomes in effect a proxy referendum. Such a contest might deliver a pro Brexit majority in the House of Commons.
But if it did, huge upheaval would follow, both on this island, where already strained cross-border relations might fully snap, and in Great Britain, where both main parties could implode, plunging the nation further into crisis.