Justice minister Phillip Lee has quit to fight the government’s Brexit policy.
The resignation comes ahead of a crunch Commons votes on Brexit.
Remain-supporting Dr Lee said: ‘If Brexit is worth doing, then it is certainly worth doing well’ and it is ‘irresponsible to proceed as we are.’
He said his main objection to government policy was over the ‘wish to limit Parliament’s role in contributing to the final outcome’ – the so-called meaningful vote amendment.
His shock departure came as David Davis warned potential Tory rebels that they cannot undo the EU referendum, ahead of a tricky 48 hours in which the Government will try to get its Brexit programme back on track.
The Brexit secretary spoke after some Conservatives signalled that they would support an amendment to the EU (Withdrawal Bill) tabled late on Monday by former attorney general Dominic Grieve giving more power to MPs.
Dr Lee said it was clear that neither the UK nor the EU will be ‘ready in time’ for Brexit on the current schedule and ‘both would suffer from a rushed or fudged agreement’.
He warned: ‘The outcome that is emerging will be neither fully to leave the EU, nor fully to stay. This is not an outcome for which anyone knowingly voted.
‘In my view, this raises the important principle of legitimacy: I do not believe it would be right for the Government to pursue such a course without a plan to seek a confirmatory mandate for the outcome.
‘And I believe that Parliament should have the power to ask the Government to adjust its course in the best interests of the people whom its members represent.’
He added: ‘If Brexit is worth doing, then it is certainly worth doing well; regardless of how long that takes. It is, however, irresponsible to proceed as we are.’
He called for Article 50 to be paused, extended or revoked to allow more time for negotiations.
He said the UK should ‘re-engage with our European and international friends to talk about how to achieve the aims that we share for the future in ways that respect individual countries’ interests and sovereignty’, taking into account concerns expressed in other EU countries since the Brexit vote about the bloc’s direction.
And he said that Parliament should be empowered ‘to direct our Government to change course in our interests’.
On the meaningful vote, he said: ‘In all conscience, I cannot support the Government’s decision to oppose this amendment because doing so breaches such fundamental principles of human rights and Parliamentary sovereignty.
‘A vote between bad and worse is not a meaningful vote. And I cannot bring myself to vote for it in the bastion of liberty, freedom and human rights that is our Parliament.’