BACKSTOP PLEDGE

"It is the Union's firm determination to work speedily on a subsequent agreement that establishes by Dec 31, 2020, alternative arrangements, so that the backstop will not need to be triggered," the 27 EU leaders said after hearing May out.

The date refers to the end of a status-quo transition period when a new EU-UK free trade pact is supposed to take effect.

"If the backstop were nevertheless to be triggered, it would apply temporarily, unless and until it is superseded by a subsequent agreement that ensures that a hard border is avoided," the statement added, before concluding: "The backstop would only be in place for as long as strictly necessary."

For now, that assurance of what is already obvious in the treaty seems unlikely to appease its British opponents. But EU diplomats said leaders were unwilling to go further.

"Our British friends have to tell us what they want," said EU chief executive Jean-Claude Juncker. "We often find ourselves in a nebulous, vague debate and it is time we got clarity."

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 to risk unravelling its own system of close integration: "We have postponed the showdown moment. It will come back in January," one EU diplomat said.

"There is little we can actually do to save the deal -- if it falls it's because there is no will in the UK parliament."

May won Wednesday's party ballot among Conservative lawmakers 200-117 but the size of the vote against her deepened divisions. Victory also came at a price - May promised she would step down by the next election scheduled for 2022.

Reuters