The outline of a potential compromise deal on Brexit has begun to emerge in Brussels with both sides now working towards a new route out of the deadlock.

EU diplomats confirmed they were looking at a new kind of legal instrument to sit alongside the existing withdrawal agreement, giving clarity over the temporary nature of the Irish backstop so hated by Tory backbenchers.

They were in meetings with the UK’s attorney general Geoffrey Cox, who has already done groundwork on similar instruments before heading to Brussels for meetings alongside Brexit secretary Stephen Barclay.

Brussels officials also signalled they were ready to redraft the language in the political declaration on future relations – the other half of the Brexit deal – with Mr Barclay having indicated earlier this week that Tory backbench proposals might be fed into it.

But the difficulty of reaching a final deal still weighed heavily on talks on Thursday, with EU officials said to be holding firm against Mr Cox’s ongoing drive for a specific end date to the backstop.

EU Commission president Jean-Claude Juncker also poured cold water on hopes of strong progress when he said he was “not very optimistic” that a no-deal Brexit can be avoided.

The sticking point to Ms May winning full support from her party for her deal has always been the backstop, an arrangement to ensure the Irish border remains open after Brexit, but one that would see the UK potentially locked into an indefinite customs arrangement at the end of 2020 if no new trade deal is signed.

The Independent reported earlier this week that Mr Cox had prepared draft proposals for a legally binding “codicil”, which would be attached to the existing withdrawal agreement, offering additional clarity as to the temporary nature of the backstop.

EU diplomats confirmed on Thursday that both sides were now moving towards some kind legal instrument separate to the main agreement.

They spoke of a “parallel declaration” or “interpretative instrument”, though it was unclear at this point exactly what it would say and if it could ever be enough to satisfy Tory eurosceptics and Ms May’s DUP allies, who want the backstop removed from the main agreement altogether.

One EU official told The Independent that Mr Cox is still pushing for an end date on the backstop as part of his proposals, but the commission is understood to be “holding firm” against the demand, “but open to some clarificatory language”.

The government may be hoping it can allay some anger from members of the Brexiteer European Research Group of backbench Conservative MPs by building some of its favoured proposals into the future trading framework.

One EU diplomat who deals with Brexit said: “We are also looking at updating the declaration on future EU-UK ties after Brexit to give more prominence to the ‘alternative arrangements’ sought by Britain.”

But the diplomat stressed that it was unlikely any of the changes would be finalised by next week, dashing any hope that Ms May could put a new deal to the Commons before the end of the month.

Instead she will face another round of attempts by backbenchers to put forward alternative plans to be voted on on 27 February.

If, as last time, there is a motion placed that would allow MPs to seize control of the parliamentary agenda and seek to delay Brexit, she could face resignations form the ministerial ranks if she stops frontbenchers backing it.

The prime minister’s aides hope that enough progress can be secured in the coming days to allow them to put a motion down on 27 February backing her strategy instead, in a bid to cement support behind it and avoid cross-party groups of MPs seizing control.

Ms May will head to Sharm el-Sheikh for a two-day EU-League of Arab States summit, where she is expected to hold a series of one-to-one meetings on the margins of the main event with EU leaders including German chancellor Angela Merkel and Irish premier Leo Varadkar.