Prime Minister Theresa May's attempt to win assurances from the European Union on her Brexit deal was cast at home as a humiliating failure that did nothing to ease the parliamentary deadlock over Britain's departure from the bloc.

With British politics in crisis, the ultimate outcome of Brexit remains unclear, with possible outcomes ranging from a disorderly Brexit with no deal to another referendum on EU membership.

Dealing with Brexit

May, who on Wednesday survived a plot in her party to oust her, asked EU leaders at a summit in Brussels for political and legal assurances that she said could convince the British Prliament to approve her deal.

German Chancellor Angela Merkel and French President Emmanuel Macron ruled out any reopening of last month's treaty aimed at ensuring a smooth exit on March 29, though leaders assured her that it should not bind Britain forever to EU rules.

“The key question is whether the PM will stand up to them or whether she will roll over as has happened previously,” said Arlene Foster, the leader of the Northern Irish party which props up May's minority government. “This is a difficulty of the prime minister's own making,” said Foster, adding that May had promised to get legally binding changes to the deal.

The opposition Labour Party said May had failed to secure changes and called for a vote next week in parliament on her deal. Sterling fell to $1.2591.

“We told Theresa May once again that we would not reopen the withdrawal agreement,” Austrian Chancellor Sebastian Kurz said. “Besides the withdrawal agreement, there is a huge understanding of both sides and a wish to find a way to deal with Brexit.”

Scotland's First Minister Nicola Sturgeon, whose Scottish National Party holds the third-largest share of parliamentary seats, said that once May's deal was defeated, parliament should seek a second EU referendum.

“Anything else now is just wasting time,” she said in a tweet.

British newspapers said May had been humiliated. “Stabbed in the backstop: EU leaders tell PM to get stuffed,” The Sun newspaper's headline said.

‘Trust me’

May asked for political and legal assurances that the so-called Northern Irish backstop would be temporary and urged the leaders to look at her track record of delivering results even when the odds looked stacked against her.

The backstop is an insurance clause obliging Britain to follow EU trade regulations until a better way is found to avoid a “hard border” between Britain's Northern Ireland and EU member Ireland.

“Over the last two years, I hope I have shown that you can trust me to do what is right, not always what is easy, however difficult that might be for me politically,” May said, according to a senior British official.

May said she believed there was “a majority in parliament who want to follow through on the referendum and leave with a negotiated deal” but cautioned that an accidental no deal was possible.

Showdown imminent?

EU leaders quashed a line in an earlier draft of their statement which had held out the prospect that further ”assurances” could be given in January.

One person briefed on the exchanges said May was “grilled” by leaders. “Everybody asked: What exactly do you want?,” he said. “She had no solid answers.”

Diplomats said May indicated she would want to come back for a second bite of “assurances” with “legal force”, and some said they would be willing to listen and try to accommodate her.

But leaders also warned that the EU was prepared for Britain to leave without a deal rather than risk unravelling its own system of close integration: “We have postponed the showdown moment. It will come back in January,” one EU diplomat said.