"We have already been laying the groundwork for an ambitious agreement with the USA through our joint working groups, which have met five times so far", the spokeswoman said.
A vote against the deal would plunge the whole Brexit scenario into unchartered water, including the prospect of Britain leaving the bloc with no deal, relying on WTO terms for its future trading with its former European Union member states.
She said: "Nothing has been settled in terms of when the debate will take place but I think this is an important moment for our country and it is right that we treat it with the seriousness it deserves. I don't think they meant that".
"I don't think that the Prime Minister meant that". "Hopefully, she'll be able to do something about that", Mr Trump said. And, I don't think they want that at all. Mrs May faces her biggest hurdle yet on December 11 with a huge uphill battle to get her deal passed through Parliament amid numerous protests from all sides it doesn't represent what the British people voted for during the European Union referendum in June 2016.
"We have already been laying the groundwork for an ambitious agreement with the USA through our joint working groups, which have met five times so far. We will have control of that and we will strike trade deals that will enhance our prosperity, enhance our economy and bring jobs to the United Kingdom". "The British people want MPs to get on with a deal and allow the country to come together", she said.
May has appealed to lawmakers from the main opposition party, Labour, to vote for her deal "in the national interest". It has been broadly supportive of the Prime Minister's draft deal.
"This is that deal".
Conservative MP Mark Francois told May her deal was "as dead as a Dodo".
"For the good of the nation, the House has very little choice but to reject this deal", he said.
Mrs May's chances of getting her deal through parliament appear slim, with it estimated she could be more than 60 votes short of winning the House of Commons support.
The agreement, which May has described as the best possible outcome for the United Kingdom and repeatedly taken to the airwaves to urge public support in the last few weeks, follows more than 18 months of negotiations between the two sides, which began when the United Kingdom triggered Article 50 in the wake of the June, 2016 referendum in favour of Brexit.
"Or this house can choose to reject this deal and go back to square one".
"No one knows what would happen if this deal doesn't pass".
May added: "Exactly how it might be done, if he takes it up, would be a matter for the broadcasters to determine". "But regardless of how it will all end, one thing is certain: we will remain friends until the end of days, and one day longer".
"My fear is that this deal gives us the worst of all worlds".
May returned to the lower chamber of lawmaking a day after European Union member states gave unanimous backing to a deal on the UK's withdrawal from the bloc but now must convince a majority of Members of Parliament to vote in its favor when it is put to a meaningful vote in the chamber.
In an interview with the Sun, he said would have done the Brexit negotiations "much differently" and claimed the PM had not listened to his advice.
Looking towards December 11, May said there is a choice the House of Commons will have to make.
Meanwhile, Downing Street chief of staff Gavin Barwell and effective deputy prime minister David Lidington invited opposition MPs to a briefing on the agreement.
"The prime minister has given up, she is saying this is where we are and we just have to accept that", Democratic Unionist Party leader Arlene Foster told the BBC.
However, Mrs May defended her Brexit plan as she embarked on a visit to Wales and Northern Ireland on Tuesday.