Boris Johnson and the European commission president, Ursula von der Leyen, will hold talks on Saturday before a potentially decisive week in the Brexit negotiations, amid growing concern in Brussels at the lack of progress. UK sources played down expectations of a breakthrough moment but with time short for parliamentary ratification the phonecall may prove to be the final chance for a political intervention in the troubled talks. “The prime minister will speak to [Von der Leyen] tomorrow afternoon to take stock of the UK-EU negotiations,” a Downing Street spokesman said. Johnson said he hoped a trade deal with the EU could be agreed, but the UK was well prepared if final-stage talks failed. “I very much hope that we will [get a deal], and obviously that depends on our friends and partners across the Channel. I think there is a deal to be done if they want to do it. If not, the country is of course very, very well prepared and as I have said before, we can do very, very well on Australian terms.” Claims that Joe Biden’s expected victory in the US presidential election had provoked the meeting were dismissed by EU and British sources as “far fetched”. Sources said the call was scheduled before election night and that uncertainty over the potential for a trade deal with the new US administration was having little or no impact on the talks. The EU’s chief negotiator, Michel Barnier, returns to London for the trade and security negotiations on Sunday. EU diplomats representing the 27 member states were told by the European commission on Friday that the next “major moment” would come at the end of next week, on Barnier’s return. The outstanding issues remain the level of access to UK waters provided to EU fishing fleets, fair competition rules for business – including rules on domestic subsidies – and the mechanism in the final treaty for resolving future disputes. EU officials close to the negotiations bemoaned a particular absence of progress on the so-called level playing field provisions to ensure neither side can deregulate to gain an advantage or unfairly subsidise businesses. There remains a lack of accord on how prohibitive the rules on domestic subsidies should be in the future treaty. Barnier told EU diplomats this week that the two sides were also struggling to agree a “credible mechanism” to ensure that social, environmental and labour standards on both sides develop in parallel. “We are nowhere,” said one source. The UK has agreed to non-regression from the current level but is resisting provisions that would tie the UK to Brussels’ rulebook in perpetuity. “Ideology is difficult to overcome,” said a source. EU sources said they hoped that the UK government’s refusal to budge was “brinkmanship” and “posturing” but they feared the two sides were doomed to run out of time, with neither willing to budge. David Frost, the UK’s chief negotiator, has been pushing for a “final arbitration” meeting between Johnson and Von der Leyen, to Barnier’s frustration. Barnier told diplomats this week the gap between the two sides remained too wide on too many issues for such a moment to deliver a solution. He told MEPs in a meeting on Wednesday that “next week is really the last chance for the British to move”. One EU official said Johnson had not shown “any grasp of the detail”. Should a deal be possible, it is hoped the 27 EU leaders will be able to sign it off at an upcoming conference call on 19 November or at a similar summit expected to be arranged soon after. Sources suggested agreement needed to be found by 12 or 13 November to allow the European parliament to start its ratification process.