The Prime Minister may not seek to reopen the Brexit Withdrawal Agreement to make changes to the controversial Irish backstop, a Cabinet minister has suggested.

Jeremy Wright implied the insurance policy to prevent a hard border could be amended via a codicil, saying the “objective” mattered more than the “mechanism”.

The Culture Secretary’s comments came hours after Theresa May wrote to Tory MPs assuring them the Government would continue its work to secure changes to the backstop, as she pleaded with them to unite and deliver on Brexit.

Mr Wright told the BBC’s Andrew Marr Show: “I think what’s obvious is that Parliament, and I think probably people well beyond Parliament, are concerned about the potential indefinite nature of the backstop – that’s what we’ve got to do something about.

“If this is the only way of doing it then that’s the way we will pursue. If there are other ways of doing it that are just as effective that perhaps we haven’t yet explored then we will do that too.”

He continued: “I don’t think it’s the mechanism that matters, it’s the objective: if you can get to a place where the potential longevity of the backstop, the potential that the backstop lasts forever can be adequately dealt with, that’s what we’re all seeking to do.”

But Tory Brexiteer Sir John Redwood said it was not possible to “gloss” the Withdrawal Agreement.

“It needs significant changes, I’m not saying a little change would be sufficient, it requires a renegotiation,” he told the Press Association.

Sir Bill Cash, Conservative chairman of the European Scrutiny Committee, said if the changes were just “flowery words” then the deal “won’t wash”.

“The backstop is unacceptable because it means that we remain in the EU indefinitely and also would do immense damage to relations with Northern Ireland … and therefore as far as I’m concerned unless the wording actually has legal force and has substance it isn’t going to work.”

Meanwhile, shadow chancellor John McDonnell said Labour would “look at” a proposal put forward by backbenchers Peter Kyle and Phil Wilson to back a second Brexit referendum.

“I met Peter and Phil last week, and what they’re saying is if Parliament does agree some form of deal, why not have a confirmation referendum after that?” he told Marr.

“We’ll look at that in the debate over the next week.”

Defence Minister Tobias Ellwood urged the Government to allow a free vote on ruling out a no-deal Brexit at the end of the month if Mrs May cannot get her deal through the Commons.

Tobias Ellwood urged the Government to allow a free vote on ruling out a no-deal Brexit (Victoria Jones/PA)Tobias Ellwood urged the Government to allow a free vote on ruling out a no-deal Brexit (Victoria Jones/PA)

He told BBC Radio 5 Live’s Pienaar’s Politics he would support such a vote, saying: “I will intend to do that. I hope I will not be tested in that way.

“I hope that we will either get the meaningful vote through or indeed measures are taken which will then allow people like myself to then express those through a free vote.”

On Saturday, Mrs May urged her party to “move beyond what divides us” and sacrifice “personal preferences” for the national interest.

After another tumultuous week in Westminster which saw tensions in the party reach boiling point, Mrs May used a letter to all 317 Conservative MPs to warn them: “History will judge us all for the parts we have played in this process.”

She said: “I believe that a country with our innate strengths, enviable resources, and enormous talent can face the future with confidence that our best days lie ahead. But we stand now at a crucial moment.

Brexit: what could happen

“I do not underestimate how deeply or how sincerely colleagues hold the views which they do on this important issue – or that we are all motivated by a common desire to do what is best for our country, even if we disagree on the means of doing so.

“But I believe that a failure to make the compromises necessary to reach and take through Parliament a Withdrawal Agreement which delivers on the result of the referendum will let down the people who sent us to represent them and risk the bright future that they all deserve.”

The Prime Minister will return to Brussels for further talks with European Commission president Jean-Claude Juncker this week, and intends to speak to the leaders of every EU member state over the coming days.

Meanwhile, Brexit Secretary Stephen Barclay will meet the EU’s chief negotiator Michel Barnier on Monday to discuss the proposals of the Alternative Arrangements Working Group of Tories, who have been seeking a compromise solution to avoid the need for backstop.

And Attorney General Geoffrey Cox will set out what changes would be required to eliminate the legal risk of being indefinitely trapped in the controversial Irish backstop in a speech on Tuesday.