While Westminster has been gripped by the Conservative leadership race, Brussels has been on a Brexit break.

That respite will soon be over. And despite rumours of Brussels compromises in the works, the EU has no off-the-shelf Brexit plan for the new prime minister, who is expected to be announced on Tuesday.

“It wouldn’t make any sense to start working on this now,” one senior EU source said. “Because we really need to know [what he wants]. The only thing we have seen are his public statements.” EU negotiators have had no contact with the teams of Boris Johnson – the widely presumed winner – or his rival, Jeremy Hunt.

Danuta Hübner, a Polish centre-right member of the European parliament’s Brexit steering group, said there was a “worrying” lack of time to find a compromise before Britain’s departure day on 31 October.

She could not imagine the EU putting anything new on the table, but said it remained open to renegotiating the political declaration on future relations. “We cannot change the major red lines on our side, that there is no possibility of renegotiating the agreement, including the backstop.”

Johnson and Hunt have vowed to tear up the backstop, the fallback plan to prevent a hard border on the island of Ireland, which both men have voted for at least once. Recent reports have suggested the EU is ready to offer a five-year transition to break the deadlock over the backstop.

But three EU sources said this was a rehash of debates from the negotiation period, rather than fresh ideas. “It’s all quite ancient” and “not something that we are considering at all”, an official said.

Quick Guide What is the Brexit ‘backstop’? Show What is the original ‘backstop’ in the withdrawal agreement? Variously described as an insurance policy or safety net, the backstop is a device in the withdrawal agreement intended to ensure that there will not be a hard border between Northern Ireland and the Republic of Ireland, even if no formal deal can be reached on trade and security arrangements. It would mean that if there were no workable agreement on such matters, Northern Ireland would stay in the customs union and much of the single market, guaranteeing a friction-free border with the Republic. This would keep the Good Friday agreement intact. Both the UK and EU signed up to the basic idea in December 2017 as part of the initial Brexit deal, but there have been disagreements since on how it would work. The DUP have objected to it, as it potentially treats Northern Ireland differently from the rest of the UK, creating a customs divide in the Irish Sea, which is anathema to the unionist party. Hardline Tory Eurosceptics also object to it, as they perceive it to be a trap that could potentially lock the UK into the EU’s customs union permanently if the UK & EU cannot seal a free trade agreement. That would prevent the UK from doing its own free trade deals with nations outside the bloc. What was added to May’s withdrawal agreement? Joint interpretative instrument

A legal add-on to the withdrawal agreement was given to Theresa May in January 2019 to try to get her deal through the UK parliament. It gives legal force to a letter from Jean-Claude Juncker and Donald Tusk, the presidents of the commission and council. This stated the EU’s intention to negotiate an alternative to the backstop so it would not be triggered, or, if it was triggered, to get out of it as quickly as possible. Unilateral statement from the UK This set out the British position that, if the backstop were to become permanent and talks on an alternative were going nowhere, the UK believes it would be able to exit the arrangement. Additional language in political declaration This emphasises the urgency felt on both sides to negotiate an alternative to the backstop, and flesh out what a technological fix would look like. However, it failed to persuade the attorney general, Geoffrey Cox, who said that while it ‘reduces the risk’ of the UK being trapped in a backstop indefinitely, it does not remove it. What happens next? Boris Johnson declared the Northern Ireland backstop ‘dead’ during his leadership campaign, and promised to throw it out of any deal he renegotiated with the EU. The EU has repeatedly stated that it will not reopen the withdrawal agreement for renegotiation. Daniel Boffey, Martin Belam and Peter Walker

Another favourite Tory idea, a time limit on the backstop, also appears to be based on bar-room conversations that took place more than a year ago rather than new proposals. Before the backstop was agreed, time limits were “mused over by individuals, typically over a beer”, said the official. The idea was never seriously discussed in the EU27’s formal negotiations and disappeared after Theresa May “embraced the backstop”, the person said.

In what is seen as a major concession to the government, the prime minister persuaded the EU to accept a UK-wide backstop, rather than the original Northern Ireland-only plan.

EU officials are also disappointed that guarantees to avoid the backstop – seen in Brussels as generous and far-reaching – did not help persuade MPs to support the withdrawal agreement, which was rejected three times.

Between December 2018 and March 2019, the EU issued three sets of promises outlining speedy work on a future trade deal to avoid the backstop. Each text became more elaborate, culminating in the Strasbourg agreement, with its pledge of joint work on “alternative arrangements” to avoid a backstop – a key phrase for Tory backbenchers.

But the Strasbourg agreement failed to move Eurosceptics who feared being “trapped” in a permanent customs union with the EU, after the attorney general, Geoffrey Cox, confirmed it provided no unilateral exit from the backstop.

Officials believe they could work on similar guarantees, but are not convinced this will help Johnson win a majority. “People say that he is better at selling things than Madame May,” said the senior source. “It’s not a huge hope.”

As Brussels waits for Johnson, the commission’s Brexit negotiating taskforce will be on standby over the summer.

Meanwhile, the EU is trying to figure out whether Johnson is serious about his “do or die” rhetoric, or will attempt the political backflip of selling a rebranded version of May’s deal. “The next British prime minister has to choose whether they want to ruin their career on Brexit or move on,” an EU diplomat said.

Some are still trying to figure our his true views on the EU. Hübner recalls a “wonderful conversation” with Johnson when, as European regional policy commissioner, she visited the then London mayor in 2008, to announce EU funds for East End startups. “He was also very positive about EU transfers to London to support a project. Now when I hear very nasty comments about the European Union, I am thinking: is this the same person?”