"If it can't then I certainly would welcome the vote being deferred until such time as we can answer that question".
Mrs May repeatedly sidestepped questions on whether she would delay the 11 December vote, but did hint at possible concessions on the backstop.
But opposition Labour Party lawmaker Chris Bryant said the agreement's vision for future relations with the European Union was "no more deliverable than a letter to Santa Claus".
"They resemble the kind of diktat that might be imposed on a nation that has suffered a military defeat".
Ministers will make the government's case during four more days of debate, but few believe they can overcome the intense opposition to the deal.
The Border Delivery Group, a Whitehall co-ordination group for Government departments that have an interest in border issues, was holding discussions with key stakeholders today, a spokesman for Mrs May said.
The prime minister's DUP allies - along with Tory MPs Philip Hollobone and Peter Bone - joined opposition parties in the unprecedented move. They fear we will be stuck in a perpetual limbo, having to implement all the rules and regulations of the European Union, but without having a say in the decision-making process in Brussels.
I don't think a second referendum is either.
The figures have been released as Mrs May desperately seeks to get parliamentary and public approval for her Brexit deal, amid fears her government could collapse if not.
While the attorney general concedes that the European Union has the competence, under Article 50, to secure an orderly withdrawal, and to build a temporary bridge to the future, he argues correctly that Article 50 can not be used to create enduring and wide-ranging future arrangements between the European Union and the UK.
Fire and Ice Collide in Game of Thrones Season Eight Teaser
This is poetic, harking back to the title of the novel series the show is based on, A Song of Ice and Fire . If the result is dragonglass, it's worth noting that's one of the few ways White Walkers can be killed .
Some Conservative MPs are pushing for a second referendum, but May warned against spending "the next decade as a country going round in circles".
Mr Lewis said: "All Jeremy Corbyn offers is more division and uncertainty".
However, the transition period could be extended for a maximum of two more years.
However, the Government has ruled out making a plea to Brussels to renegotiate the withdrawal agreement.
Visits were being made to schools, hospitals, workplaces and a butcher's shop in East Anglia in a bid to build support among regional audiences, with many taking place outside the gaze of the national media.
Both May and the bloc insist the withdrawal agreement can't be changed, and rejecting it means leaving without a Brexit deal.
Meanwhile supporters of the beleaguered PM published a plan to reduce the chances of the Northern Ireland backstop coming into force - in the hope it would help the deal pass in parliament. And neither Ireland or Northern Ireland wants such a border.
However, it has already been rejected by Arlene Foster, leader of the Democratic Unionist Party, which is propping up Mrs May's government.
MPs on Tuesday backed an amendment tabled by Conservative former attorney general Dominic Grieve that would allow the Commons to amend that motion.
The legal advice - which the British government was forced to publish after being found in contempt of parliament for not doing so - flew in the face of the assurances from Mrs May and from other ministers that the backstop would only be temporary and that Northern Ireland would be treated in exactly the same way as the rest of the UK.
However after seeing the document, Labour shadow attorney-general Sir Keir Starmer said "all this advice reveals is the central weaknesses in the government's deal".