Theresa May faces humiliation in a critical vote this evening on her Brexit deal after an amendment that could have reduced the size of a rebellion was withdrawn at the eleventh-hour.

Labour MP Hilary Benn, who chairs parliament’s Brexit Committee, had tabled his motion that would have rejected the UK leaving the European Union without a deal and, crucially, the prime minister’s deal.

If the amendment had passed, it would have prevented MPs from voting on the main motion - whether to simply accept or reject Ms May’s deal reached with the bloc.

Following concerns this move could have reduced the scale of a any potential defeat for the prime minister - as many Brexiteers opposed to the deal would not vote to rule out a no-deal scenario - Mr Benn said he was withdrawing his amendment.

The former shadow foreign secretary said it is now “vital that we get the clearest expression of the view from the House on the government's deal”, which is expected to be voted on after 7pm on Tuesday.

Mr Benn added that since he had originally tabled his amendment in December, MPs had voted for a no deal amendment to the Finance Bill "which is a clear and very welcome indication of MPs' opposition to no deal".

He said Dominic Grieve's amendment and the Speaker's ruling that a business motion can be amended "are also very important and there is now a proposal for a Bill that would allow the Commons in effect to rule out a no deal Brexit by seeking an extension to Article 50 if necessary".

"All these developments mean that the House will soon have the opportunity to make it clear that it rejects no deal and so offer reassurance to the many businesses and their workers who are very anxious about the disaster that a no deal Brexit would represent.

"If the prime minister loses tonight the government must reach out across the House to try and find a way forward. If this doesn't happen, then Parliament will have to take the lead."

It comes on a historic day at Westminster, with the prime minister facing an all but certain defeat on the Brexit deal she has spent the last 19 months negotiating and countless hours attempting to defend at the despatch box.

Brexit Withdrawal Agreement: How might MPs vote

But with more than 100 Conservative MP having expressed their opposition to Ms May’s deal in recent weeks - and her supply and confidence partners, the DUP, vehemently opposed - there is speculation the government could be facing one of the heaviest defeats in modern British political history.

Former Labour prime minister Ramsay MacDonald suffered the greatest defeat in the last century when he lost a vote by 166 votes in 1924, according to the political academic Philip Cowley.

Police separate clashing Brexit protesters outside Parliament Show all 11 1 /11 Police separate clashing Brexit protesters outside Parliament Police separate clashing Brexit protesters outside Parliament Anti-Brexit protester Steve Bray (left) and a pro-Brexit protester argue as they demonstrate outside the Houses of Parliament Getty Images Police separate clashing Brexit protesters outside Parliament A pro-Brexit protester argues Getty Images Police separate clashing Brexit protesters outside Parliament Police surround the pro-Brexit protester after he confronted Steve Bray, a pro-European protester Getty Images Police separate clashing Brexit protesters outside Parliament A leave supporter is spoken to by a police officer as he argues with a remain supporter, Steve Bray, outside Parliament PA Police separate clashing Brexit protesters outside Parliament MPs in Parliament are to vote on Theresa May's Brexit deal next week after her December vote was called off in the face of a major defeat Getty Images Police separate clashing Brexit protesters outside Parliament A leave supporter is spoken to by a police officer PA Police separate clashing Brexit protesters outside Parliament Police look on as anti-Brexit protesters demonstrate outside the Houses of Parliament. Getty Images Police separate clashing Brexit protesters outside Parliament Police hold back a leave supporter PA Police separate clashing Brexit protesters outside Parliament A police officer speaks with anti-Brexit protester Steve Bray Getty Images Police separate clashing Brexit protesters outside Parliament Police surround a pro-Brexit protester after he confronted a pro-European protester Getty Images Police separate clashing Brexit protesters outside Parliament Conservative MP David Davies, wearing a gopro camera, speaks to anti-Brexit protester Steve Bray Getty Images

Appearing on BBC Radio 4’s Today programme, however, Michael Gove, the environment secretary channelled the popular fantasy drama Game of Thrones as he issued a warning to MPs wanting to vote down the deal.