It is almost impossible to make sense of Theresa May's negotiating tactics. Again and again she has taken up positions which are self-contradictory. Another example came over the weekend, when in a cosy and relaxed TV chat she explained her overtures to the Labour Party as being necessary to ensure Britain left the European Union. No Brexit or her (modified) deal were the clear alternatives she presented.
This was obviously addressed to the Conservative Party, which is finding it extremely hard to digest the fact that she has reached out to Labour leader Jeremy Corbyn in the hope of finding common ground. In other words Tories who want Britain to leave the EU have to hold their noses and swallow. When she'd agreed a deal with Mr Corbyn they had to support it - or else, horror of horrors, Britain stays in the EU.
Unfortunately for her, however, there is no way the television audience can be restricted to Eurosceptic Tories, who she seems to assume will pay any price in return for leaving the EU. But Labour was listening too. And they didn't hear what Tories heard. They heard her say that the way to ensure Britain did not leave the EU - which the overwhelming majority of Labour MPs and party members want - was to make sure she did not get her deal through. Not horror of horrors but hurray hurray. Why on earth should Labour agree to make a deal with her in order to frustrate the one thing they devoutly wish for?
The one possibility that might make sense of her position is if she assumes that Labour, or at least its present leadership, really is keen on leaving the EU but doesn't like to say so. But even if it's true, the Labour leadership cannot deliver the votes of the Parliamentary Labour party to support that. The majority is for remain, by means of a second referendum if necessary, and if push comes to shove, it is for revoke. The Government would have to tell the EU that the United Kingdom wanted to stay in the EU after all. And the law allows for unilateral revocation.
Maybe she even thinks she can split the Labour party on this point, delivering a tactical gain for the Tories. But manifestly any such gain, unlikely though it is, would be vastly outweighed by the damage to Tory unity, which is guaranteed.
Another example. She is now engaged in trying to modify her EU deal to bring Labour on board. That means conceding that Great Britain and Northern Ireland would remain inside the EU customs union, while moving close to the EU single market. Such a concession would mean amending the political declaration which accompanies the withdrawal agreement. It is assumed the EU would agree to this, even at this late stage. But unlike the withdrawal agreement itself, the political declaration is not legally binding. It would not bind a new leader of the Conservative Party.
Yet she has promised to stand down as their leader once her withdrawal agreement and the attached political declaration has been agreed by Parliament. So she cannot keep her promise, and her most likely successor, Boris Johnson, has sworn to annul it. During a Tory leadership campaign he will stump up and down the country saying so. Labour knows this. It is obvious.
So assuming Labour is prepared to play ball at all, how can they make it stick? There has been loose talk about passing a law to bind the Conservative to honour a customs union deal, if necessary against the will of the leader. But laws can be repealed, and it is a dead certainty that Mr Johnson will commit to doing just that. In any event, Mr Johnson thinks Britain should leave the EU with no deal at all, rather than with Mrs May's deal, amended or not.
There is one way, and only one way. And that is to put "May's deal plus customs union" to a vote of the general public. Were it to be carried, Boris Johnson - who insists referendum results are binding - would have to accept it. And Labour's deal with Mrs May would be set in concrete. Mrs May doesn't seem to realise her offer to Labour logically requires another referendum. Like so much else about her negotiating style, she has not thought it through.
Clifford Longley will be writing regular updates on Brexit over the coming weeks. To read more click on the links below.