Theresa May's grip looks weak as Brexit deal vote nears

Britain's Prime Minister Theresa May leaves Downing Street. Photo / AP

Two members of the British Government are resigning and a Cabinet minster is mulling whether to quit over Brexit as Theresa May's Administration appears to be disintegrating ahead of an important vote.

Government whips gave Conservative MPs until today to set out how they will vote on the Prime Minister's Brexit deal, in a desperate bid to judge the scale of a rebellion that threatens to bring down her Government.

Will Quince MP, a member of the Defence Secretary's ministerial team, has announced he is quitting his government role, saying he wants to "implore the Prime Minister to go back to the European Union and find another way".

A second parliamentary private secretary plans to quit tomorrow, while a number of senior party figures were "wrestling with decisions to resign".

More resignations are possible from the Cabinet, with leading Brexiteer Penny Mordaunt said to be deciding over the next 48 hours whether to back the deal or quit in what one minister described as "the week of unknowns".

In a clear indication that Britain could be on the verge of a re-alignment of politics along Remain/Leave lines, as many as 100 MPs - including 35 Tory MPs - are prepared to publish a motion calling for a vote on the terms of the UK's exit immediately after May's deal is voted down on Wednesday NZT.

The amendment, tabled by Tory MPs Sarah Wollaston and Heidi Allen, will be attached to any attempt by May to bring back her deal for a second vote in the House of Commons.

May's leadership rivals are preparing to move quickly if she resigns, with Boris Johnson described as "focused" by friends and Sajid Javid and Jeremy Hunt plotting to run on a joint ticket.

Officially, Downing Street continued to insist yesterday that the meaningful vote on Britain's exit from the EU would go ahead, with one official saying they were "100 per cent" certain that the vote will be held. A final ruling from the European Court of Justice is expected tomorrow to say that Britain will be allowed to delay Brexit from March 29 without asking for permission from the other member states.

Andrew Mitchell, a former chief whip, became the 105th Tory MP to oppose the deal, saying that May's strategy of going ahead with the vote "appears to have as its inspiration the Charge of the Light Brigade". Behind the scenes May is being urged to delay the vote.