Brexit rebels have told City A.M. the government's new law "shall not pass" unless key amendments are made - but stressed they are not frustrating the process.
Several Conservative MPs were outed by the whips' office last night as "mutineers", who are seeking to thwart the process.
But today they have fought back, insisting they are on board with the process - as long as the government concedes ground on areas such as the so-called Henry VIII powers and the inclusion of the time and date of Brexit.
Sarah Wollaston, who has already voted against the government on Universal Credit, told City A.M. the whips' briefing was "more likely to have the reverse effect than the one intended".
The Remain voter said: "A lot of us find it really annoying to be portrayed as Brexit mutineers, because it’s actually about what happens after Brexit that matters. This is not about frustrating the referendum: it's about making a better Brexit.
"We need to reform secondary legislation in any case, but the sheer volume of it after Brexit, and the consequences it will have for everyday lives, makes it absolutely essential we have the ability to do so now
"I don't think anybody voted to take back control for a handful of ministers."
Wollaston said ministers would "have to listen" to those pushing for changes to the bill. "There are sufficient numbers of us now - the maths is such that they must listen to the will of parliament" she said. "This will not pass as currently set out. It absolutely will not pass the Commons."
Dominic Grieve, former attorney general and the man behind many of the amendments, agreed. "Anyone who has been listening to what we've been saying will realise that none of us... wish to prevent Brexit from taking place. We are trying to improve legislation."
"I am wholly happy to be a called a mutineer if people are saying I'm a mutineer from a government amendment which I think is mistaken, foolish and counterproductive," he said, in reference to David Davis' last minute introduction of the time and date into the bill.
Grieve noted there was "widespread" concern among MPs, many of whom would vote with their feet, but stressed this "important legislation" should be allowed to progress through parliament.
"The government could start the whole process again, but it would put the timetable back and we are very short of time," he noted.
Chair of the Treasury select committee Nicky Morgan said this was "the bread and butter of being an MP".
"Parliament accepts we are leaving the EU in March 2019, but we are not going to sign off on doing it in a harmful way, nor without parliment being involved in scrutinising legislation in a meaningful way. It is up for the backbenchers to challenge the government [and] we will not accept the end date being on the face of the bill."
Conservative colleague Anna Soubry told the House she had received a number of death threats since being named, which she has passed onto the police.
And during today's PMQs, Tory Michael Tomlinson, asked Theresa May to defend MPs' right "to scrutinise, to debate considered amendments" saying it was important that "we come together and deliver Brexit for our country and the British people."
Theresa May replied: "There is of course a lively debate going on in this place... and there are strong views held on different sides of the argument, on both sides of this House. We are listening to the contributions being made, we are listening carefully to those who wish to improve the bill and I hope we can all come together"