Boris Johnson and the European commission president, Ursula von der Leyen, will speak on Saturday in an attempt to unblock talks on a post-Brexit trade deal. Why is Boris Johnson talking to Ursula von der Leyen on the phone? After nine months of negotiation on the future relationship between the UK and the EU, the two chief negotiators, Michel Barnier and David Frost, are rubbing against their red-lines in key areas, and it now requires a political intervention. Some of those red lines will have to be pinked, at the very least, for a deal to be secured. That requires political direction. Frost and Barnier issued a joint statement on Friday evening calling a temporary halt to their talks. “After one week of intense negotiations in London, the two chief negotiators agreed today that the conditions for an agreement are not met, due to significant divergences on level playing field, governance and fisheries,” Barnier and Frost said in their statement. “On this basis, they agreed to pause the talks in order to brief their principals on the state of play of the negotiations.” What is the problem? Despite the headlines, fishing is not the dealbreaker. Downing Street briefed that last-minute EU demands for a 10-year transition period for changes to fishing access for European fleet in British waters had rocked the negotiation. But the two sides have been discussing the terms of a transition period for months, and a compromise will be found. The more significant issues lie in Barnier’s demands for provisions to ensure that Brussels can unilaterally hit back at British economic interests if the UK diverges from EU environmental, labour and social standards. It is a matter of principle to the government that policymakers in Westminster need not be boxed into following EU standards. There is a dispute over how to define the common high standards from which neither will regress. As EU and UK policy develops, there is also not yet agreement on a mechanism to ensure undercutting comes with consequences. Meanwhile, the EU is concerned about the UK’s future regime for controlling domestic subsidies, or state aid. It wants an independent regulator in the UK to act on treaty-embedded shared principles with the option of taking unilateral action to suspend parts of the deal or apply tariffs where it is feared that a subsidy will distort trade. For Downing Street, this smacks of EU state aid rules being applied in the UK via the backdoor. In short, Johnson has always said that Brexit is about divergence but the EU does not want to offer up “zero tariff, zero quota” access to its single market to British companies if they are able to operate with lower costs bases due to differing regulations in the UK. It is a matter of self-protection. What will it happen? Saturday is not deal day. Anything agreed in terms of pinking the red-lines will be passed down to the negotiators who will work on legal text. This will then be presented to EU ambassadors in Brussels and the cabinet in Westminster as early as Sunday for scrutiny. Only then will it be clear if there is a deal. It could plausibly be no-deal day if Johnson and Von der Leyen both take a rigid approach to these issues. UK government sources have said there is only a 50% chance of success. Barnier was quite downbeat as he left London for Brussels on Saturday morning, telling reporters that the two sides would need to see if there was “still” a way forward. EU sources suggest, however, that agreement is within reach and the problems are resolvable. In Von der Leyen, Johnson is dealing with a negotiating partner that sorely wants an accord and is willing to challenge the resistance of some member states on concessions. Much depends on whether the prime minister feels the same.