Less than four months until the UK is due to leave the EU on March 29, May finally accepted that British lawmakers would reject her deal, so on Monday she pulled a vote on it in the UK parliament..

But she said the only other options were a disorderly no-deal divorce, or a reversal of Brexit that would defy the will of those who voted for it.

In a bid to save her deal, May sought support from Dutch Prime Minister Mark Rutte whom she met in The Hague for breakfast on Tuesday. She will later meet German Chancellor Angela Merkel in Berlin.

The message from Europe was clear: It will give clarifications but not countenance reopening the treaty.

"The deal we achieved is the best possible. It's the only deal possible. There is no room whatsoever for renegotiation," European Commission head Jean-Claude Juncker said in an address to the European Parliament in Strasbourg.

The most contentious issue has been the Irish "backstop", an insurance policy that would keep Britain in a customs union with the EU in the absence of a better way to avoid border checks between Northern Ireland and EU member Ireland.

May's critics say it could leave Britain subject to EU rules indefinitely.

Juncker said neither side intended for the backstop ever to take effect, but it had to remain a part of the deal.

"We have a common determination to do everything to be not in a situation one day to use that backstop, but we have to prepare," he said.

Germany's European Affairs Minister Michael Roth said the EU did not want Britain to leave but added that substantial changes to the withdrawal agreement would not be possible.

"Nobody wants the UK to leave," Roth said. "I cannot imagine where we could change something substantial in the withdrawal agreement."

May, due to meet Juncker and European Council President Donald Tusk later, said she would seek further assurances and ways to give British lawmakers powers over the Irish backstop.

As investors and allies tried to work out the ultimate destination for the world's fifth-largest economy, rebel lawmakers in May's party said she had to go.

"If we can't go forwards with her deal ... then I'm afraid the only way to change the policy is to change the prime minister and I really think it's her duty to go," Brexit-supporting Conservative lawmaker Steve Baker said.

A leadership challenge is triggered if 48 Conservatives write letters demanding one to the chairman of the party's so-called 1922 committee, Graham Brady.

With little hope of substantial changes from the EU, the options open to Britain range from a chaotic Brexit with no deal to risking the wrath of pro-Brexit voters by calling the whole thing off.

Among Brexit opponents there is mounting enthusiasm for a chance to have another say in a second referendum on whether to leave the EU..

Australian Associated Press