European Union leaders have said the Brexit withdrawal agreement is “not open for renegotiation”, after appeals from Theresa May.
She wants legal assurances on the Irish backstop to help her deal get through Parliament, after she delayed a Commons vote in anticipation of defeat.
The PM said the deal was “at risk” if MPs’ concerns could not be addressed.
European Commission president Jean-Claude Juncker said there could be clarifications but no renegotiation.
He urged the UK to set out more clearly what it wants, adding that the commission will publish information on 19 December on its preparations for a no-deal Brexit.
“Our UK friends need to say what they want, instead of asking us to say what we want, and so we would like within a few weeks our UK friends to set out their expectations for us, because this debate is sometimes nebulous and imprecise and I would like clarifications,” he said.
Mrs May travelled to Brussels to make a special plea to EU leaders at Thursday’s summit, but BBC political editor Laura Kuenssberg said it appeared that the meeting went badly and EU leaders doubted her political ability to get the deal through the Commons.
Shadow Brexit Secretary Sir Keir Starmer said Mrs May had failed to get meaningful changes and she should reinstate the vote on her deal next week.
But Cabinet minister David Lidington described the meeting as a “welcome first step” in showing that the EU was committed “to negotiate a trade deal with the UK speedily”.
The PM’s visit came at the end of a week that has seen her first delay the vote on the withdrawal agreement in Parliament, then win a vote of no confidence brought by MPs unhappy with it.
She vowed to listen to the concerns of the 37% of Tory MPs who voted against her, and was hoping to “assuage” their concerns about the controversial “backstop” plan in the agreement.
Critics say the backstop – aimed at preventing a hard border in Northern Ireland – would keep the UK tied to EU rules indefinitely and curb its ability to strike trade deals.
Conservative MPs demanded changes to the backstop to make it clear that it could not last forever, and the UK could terminate the arrangement on its own.
If this meeting in Brussels was meant to provide Theresa May with the beginnings of an escape route from her Brexit conundrum, the signs are not good.
At one of her most vulnerable political moments, Number 10 was hopeful at least of an indication of a potential solution to the most intense of a long list of Brexit problems – the controversial so-called backstop designed to guarantee against a hard Irish border.
But right now, that’s simply not on offer.
EU leaders made plain their warnings that their divorce deal with Britain was not up for negotiation were real.
Requests for change to ease Westminster politics were not fulfilled, with key phrases from a more accommodating draft gone by midnight.
But the rejection gives succour perhaps to those in government who want their critics to accept that the prime minister’s deal may be genuinely, as good as it gets.
In comments released by Downing Street on Thursday, Mrs May urged EU leaders to help her “get this deal over the line” and said she firmly believed it could get through the Commons, saying: “There is a majority in my Parliament who want to leave with a deal so with the right assurances this deal can be passed. Indeed, it is the only deal capable of getting through my Parliament,” she said.
