BRUSSELS — Embattled British Prime Minister Theresa May met sympathy but a firm rebuff on a lightning tour of European capitals on Tuesday, with EU leaders ruling out any renegotiation of the Brexit deal.

A day after she postponed a crucial vote on the accord in the British parliament, May said she was urging EU counterparts to give a "reassurance" that a measure designed to avoid a hard Irish border would only ever be temporary.

After a "long and frank discussion" with May the president of the European Council, a frustrated Donald Tusk, said he did not know what more they could do.

In a tweet, he said it was clear that European leaders wanted to help, but added: "The question is how."

In The Hague, Berlin and Brussels, May was told that, while some clarification about how the agreement will be interpreted is possible, the accord itself must stand.

After her talks with May, Merkel told lawmakers of her CDU/CSU bloc that she saw "no way to change" the agreement, according to sources at the party meeting.

May faces criticism in parliament over the so-called Northern Ireland "backstop" and hopes reassurances that it will not be invoked will persuade her rebellious Conservative party to support it.

"Whatever outcome you want, whatever relationship you want with Europe in the future, there’s no deal available that doesn’t have a backstop within it," May told the BBC.

"But we don’t want the backstop to be used and if it is, we want to be certain that it is temporary, and it’s those assurances that I’ll be seeking from fellow leaders over the coming days."

’The only deal possible’

In Brussels, May also met European Commission chief Jean-Claude Juncker for just over an hour, but neither made public statements and the EU leader’s office said they would not react until Wednesday’s regular press briefing.

Juncker said ahead of the meeting that he was "surprised" at being asked for more talks since EU leaders had given their approval to the deal at an extraordinary summit on November 25.

"The deal we have achieved is the best deal possible, it’s the only deal possible," he told the European Parliament in Strasbourg.

"There is no room whatsoever for renegotiation but of course there is room, if used intelligently, to give further clarification and further interpretations."

MPs in the House of Commons were due to vote on the deal on Tuesday night, but May deferred it on Monday, admitting she expected to lose by a "significant margin".

Her spokesman said on Tuesday the vote would be rescheduled before January 21, with Britain due to leave the EU on March 29.

Opposition Labour leader Jeremy Corbyn is now facing calls to table a no-confidence vote in the prime minister, but is holding off as the party believes May is likely to win.

Eurosceptic MPs in May’s Conservative party have also repeated calls for her to be replaced, with one warning it was time to "govern or quit".

Tusk has called a special meeting of the other 27 EU leaders for Thursday to discuss the latest developments.

They were due to meet Thursday and Friday at a regular summit where May was expected to put her case.

’I’m very worried’

Irish Foreign Minister Simon Coveney said his government ruled out changes to the wording of the withdrawal agreement, but said there could be "a political declaration coming from a European Council".

"The Irish government doesn’t have an issue with providing reassurance if that’s helpful," he told national broadcaster RTE.

May is to visit Dublin Wednesday to meet Prime Minister Leo Varadkar.

The backstop provision is designed to prevent a hard border reappearing between Ireland and Northern Ireland.

But critics say it risks tying Britain into a customs union with the EU for years after it leaves the bloc -- far from the clean break that eurosceptics want.

One of May’s ministers, Martin Callanan, said in Brussels on Tuesday that Britain was seeking "additional legal reassurances that the UK cannot be permanently trapped in the Irish backstop".

Even if no deal is secured, Britain remains on course to leave the EU on March 29 -- a scenario the government has warned will be hugely damaging to the economy.

Tusk said Thursday’s EU meeting would cover no-deal plans, while May’s cabinet was also due to discuss the issue on Wednesday.

France’s minister for European affairs, Nathalie Loiseau, said the possibility of no deal was "not unlikely", adding: "I’m very worried." — AFP