Theresa May was under renewed pressure from Brexiteers to secure fresh concessions on the Northern Irish backstop as Dublin warned there was no room for manoeuvre on the issue.
As the Prime Minister faced another Commons showdown over her EU withdrawal agenda on Tuesday, Downing Street was battling to keep control of the Brexit timetable.
In a pointed intervention, arch-Brexiteer Boris Johnson insisted he had it from “senior sources” the PM was planning to go to Brussels to renegotiate the backstop and win a “freedom clause”.
However, Ireland’s deputy prime minister Simon Coveney insisted there would be no changes to the Withdrawal Agreement which states the UK will obey EU customs rules if no wider deal has been struck after a transition period.
Mr Coveney said the backstop was crucial in preventing a hard border.
He told the Press Association: “Peace and the Good Friday Agreement are more important than Brexit.
“Even in a no-deal Brexit situation every party and every MP in the UK will have a responsibility to ensure there is no return to a hard border and Northern Ireland is protected.
“That won’t be easy and those who misrepresent the backstop don’t have an alternative to it.”
Mr Coveney’s comments were seen as a swipe at Tory Brexiteers hoping to use Commons amendments on Tuesday to try and force a change in direction on the backstop.
Attention is focusing on an amendment by Tory grandee Sir Graham Brady which calls for the removal of the backstop and “alternative arrangements” to be put in its place.
Brexiteers say if the non-binding amendment is passed it will give the PM more leeway to win concessions from the EU.
Sir Graham, who is chairman of the highly influential 1922 Committee of backbench Tory MPs, told BBC Radio 4’s Today programme the amendment would give “enormous firepower” to the Prime Minister in Brussels.
Asked if it had Government backing he said: “I hope so... I don’t know so. The amendment was born out of a number of conversations I had with colleagues including members of the Government, including the Prime Minister.
“I had also spoken to people in the DUP too and I’m hoping that the way in which the amendment is crafted can attract that very broad support and if we can win the vote on my amendment then I think it gives the Prime Minister enormous firepower.”
Meanwhile, pro-Europe amendments pose a threat to Mrs May’s grip on Brexit.
The Government is thought to be particularly concerned about a cross-party backed amendment put forward by Labour’s Yvette Cooper which is aimed at stopping a no-deal exit and paving the way for keeping the UK in the EU until the end of the year.
Tory former minister Nick Boles, a leading supporter of Ms Cooper’s plan, told Today there was a “great deal of support among ministers and, indeed, Cabinet ministers” and they had been pressing for a free vote on the amendment.
“This is the last chance for Parliament, this is probably the only opportunity that Parliament is going to have to intervene in this process, to take control,” he said.
“If we don’t seize the moment tomorrow afternoon then we are at grave risk of just driving off the edge on March 29 without really wanting to, and when there might be a compromise we could achieve if we just had a few more months.”
The Daily Telegraph reported that the PM is seeking to see off the threat of a Tory rebellion, and the possibility of ministerial resignations, by considering whether to hold a “meaningful vote” on Brexit within the next fortnight.
A dozen pro-European ministers including Work and Pensions Secretary Amber Rudd and Justice Secretary David Gauke held a conference call in which they agreed such a move would help defer a potential rebellion, according to the newspaper.
Writing in the Daily Telegraph, Mr Johnson called on the PM publicly to confirm a “change of heart” on the withdrawal deal.
He said: “That backstop is dead, rejected by the biggest ever parliamentary majority; and that is why I hope and pray that I am right about the intentions of Number 10.
“If we mean it, if we really try, I have no doubt that the EU will give us the Freedom Clause we need.
“And if the PM secures that change - a proper UK-sized perforation in the fabric of the backstop itself - I have no doubt that she will have the whole country full-throatedly behind her.”