She told BBC's radio program that she was talking to her colleagues about their concerns over the Northern Irish backstop, on which experts say the December 11 parliament vote on the Brexit deal would hinge.
They said the only question was whether Theresa May would attend the summit, raising the prospect of her quitting as prime minister after a heavy defeat on the deal.
'We built exitbrex.it to be the quickest and easiest way for people to let their MP know how they feel about Brexit'.
"I will not vote for the Prime Minister's blank cheque and I will oppose a no deal Brexit with every fibre of my being".
It would also involve a temporary single custom territory effectively keeping the whole of the United Kingdom in the EU customs union - until both the EU and United Kingdom agree that it is no longer necessary.
What Theresa May sketched out on Thursday was the idea of allowing MPs to choose when and if they want to go into the controversial "backstop" - the insurance policy against a hard border on the island of Ireland.
May used an interview on BBC radio to press on with her bid to persuade lawmakers to back her deal.
But it crosses a key red line for Brexiters by continuing freedom of movement, one of the preconditions of single market membership.
He also noted that the backstop arrangement would be "enormously complex" for the European Union, requiring "considerable resources", meaning Brussels would come under pressure - especially from Dublin - to bring it to an end.
Thank you for your feedback. The deal is unpopular and widely expected to be rejected by parliament.
Former foreign minister and leading Brexit campaigner Boris Johnson said May was wrong to say parliament might be able to choose whether to trigger the backstop or extend a transition period, under which more European Union membership terms would apply.
She added: "There are pros and cons to both sides of that". The proposal has sparked opposition from all sides because of concerns it would drive a wedge between Northern Ireland and the rest of the United Kingdom while leaving the country tied to the European Union indefinitely. But in the backstop we have no financial obligations, we have no free movement, and we have very light level playing field rules with the EU.
Mr Whittaker (Calder Valley) said: "As the deal is only about the withdrawal and implementation period, I am quite pragmatic about the agreement".
But many members of Parliament worry that the transition period is a bridge to nowhere.
A day after she faced a humiliating defeat in the House of Commons as MPs voted to hold her government in contempt over a refusal to publish the document, May laid out the six-page document in the public domain attracting allegations of "inadvertently misleading" Parliament by some MPs.
He placed a 10 percent probability on a no-deal Brexit, down from 20 percent, and a 50 percent probability on an orderly Brexit, down from 60 percent.
The remaining 630 constituencies are against her vision for Brexit, according to the poll which was released just four days before MPs are due to vote. "In my view if we do that type of Brexit, it's effectively pointless". If May loses the vote next week, the government has 21 days to return to MPs to propose what happens next.
She said those backing a second referendum wanted the public to give a different message.
The EU's chief Brexit negotiator, Michel Barnier, also tried to quash the hopes of anyone who thought another deal with the EU might be possible.