European Union leaders said on Thursday that the Brexit deal the bloc signed with Britain is not open to renegotiation. British Prime Minister Theresa May had said earlier this week that the deal was “at risk” if the country’s MPs did not agree to it.

May on Wednesday won a vote of confidence after the MPs of her Conservative Party supported her 200 votes to 117 in the House of Commons. The vote was held days after 48 of her party’s MPs called for a secret ballot, expressing disapproval for the prime minister’s Brexit policy and accused her government of betraying the 2016 referendum result.

On Thursday, May travelled to Brussels, Belgium for the European Union’s summit, to seek reassurances from the bloc’s leaders on the Irish backstop matter. However, European Commission President Jean-Claude Juncker said there could be clarifications but no renegotiation of the agreement, BBC reported.

British and European Union leaders last month committed to avoiding a “hard border” between Northern Ireland and the Republic of Ireland after Brexit. The backstop is a “safety net” which will preserve a border without customs and regulatory checks through a series of measures. There are differences between the United Kingdom and the European Union over the terms of this backstop.

“Our United Kingdom friends need to say what they want, rather than asking what we want,” Juncker said on Thursday according to The Guardian. “We would like in a few weeks for our UK friends to set out their expectations because this debate is sometimes nebulous and imprecise and I would like clarifications.”

A BBC reporter quoting an unidentified diplomat in Brussels as saying that May’s address at the summit was “bad” and “vague”, and “not very clear”.