Theresa May has begged Tory rebels not to undermine her Brexit negotiating position on the eve of key votes in the Commons.
Addressing Conservative backbenchers in Westminster on Monday evening, the Prime Minister warned if a series of Lords amendments to the EU Withdrawal Bill are approved by MPs, it will send the wrong message to Brussels.
Among the 14 amendments to the Bill - set to be voted on by MPs on Tuesday and Wednesday – are changes which would see the UK stay in the Single Market and would allow Parliament to dictate future negotiating terms.
With the Conservatives having a majority of just 13 thanks to the support of the DUP, it would only take a handful of Tories to side with Labour and defeat the Government.
Speaking to a packed meeting of Tory MPs - including Chancellor Philip Hammond, Brexit Secretary David Davis and Environment Secretary Michael Gove - May said: “We must think about the message Parliament will send to the European Union this week.
“I am trying to negotiate the best deal for Britain.
“I am confident I can get a deal that allows us to strike our own trade deals while having a border with the EU which is as frictionless as possible.
“But if the Lords amendments are allowed to stand, that negotiating position will be undermined.”
One of the key points of difference between the Prime Minister and the rebels is a Lords amendment which states the Government must seek to negotiate a customs union with the EU.
The Government is against the plan, believing it sends the wrong message to Brussels regarding the UK’s negotiating goals.
Speaking to reporters outside the meeting, Solicitor General Robert Buckland confirmed the Government was in discussions with rebels about establishing a fresh amendment committing to seek a customs arrangement - not a union - with the EU.
It is believed the change of language would carry the support of Remain and Brexit backing MPs.
Brexit Minister Steve Baker said the Government would “look very carefully” at the amendment, which is being tabled by former Cabinet Ministers Oliver Letwin and Nicky Morgan.
“We all hang together or we will hang separately,” Buckland added, in a plea for unity.
Chelmsford MP Vicky Ford, a former MEP who has frequently spoken out against Brexit, joined in the call for unity as she left the meeting.
She told HuffPost UK some of her colleagues needed to “take a chill pill”.
George Freeman, Downing Street’s former policy guru who also backed Remain in the referendum, said the main issues was “sending the PM into the negotiations with strong authority”
MPs will spend a total of 12 hours debating and voting on 14 Lords amendments to the EU Withdrawal Bill – six hours on Tuesday and six hours on Wednesday.
It is expected that Tuesday will see MPs decide whether Parliament should have the power to set the Government’s negotiating goals if Theresa May’s deal with Brussels is voted down.
The current ‘meaningful vote’ offered by the Government allows MPs to accept or reject the Brexit deal, but the proposed change would see MPs take control of the negotiation aims.
Conservative MP Sarah Wollaston said on Monday morning she was “minded” to defy party orders and back the meaningful vote amendment.
“This isn’t about narrow party politics,” she told BBC Radio 4’s Today programme.
Another key vote is on keeping the UK in European Economic Area, but the proposal has little chance of making it through as Labour is likely to tell its MPs to abstain on the vote.