Up to 25 Tory MPs are preparing to support a plan to take a no-deal Brexit off the table in a bid to force hardline Eurosceptics to support the deal.

The Cooper-Letwin plan would force the prime minister to seek a Brexit delay instead of pursuing no deal if her current plan doesn't win the backing of parliament.

Moderate MPs think that taking no deal off the table could force hardline Brexiteers to support the prime minister's Brexit plan.

An MP behind the plans said that a win for the amendment would fire a "warning shot" to those MPs opposing to the deal.

LONDON — A plan by Remain-supporting MPs to force Theresa May to take a no-deal Brexit off the table could be the key to passing her Brexit deal, growing numbers of Conservative MPs now believe.

A Brexit amendment, due to be brought forward next week by Labour MP Yvette Cooper and Conservative MP Oliver Letwin, seeks to force the prime minister to request a delay to Brexit.

The amendment would not automatically delay Brexit. However, supporters of May's deal have told Business Insider that they believe it will be a sufficient "warning shot" to bring Conservative Brexiteers back into the fold and are now planning to support it.

"I can confidently say there will be 25 or 30 Tory MPs [in the centre-ground Brexit Delivery Group of Conservative MPs] who would support Cooper-Letwin," a prominent member of the group told Business Insider.

One member of the group, which is largely in favour of passing May's deal, said that a win for the amendment could bounce MPs opposed to the deal into supporting it because it would create a choice between the PM's deal and a lengthy delay to Brexit. They said this would "sharpen the minds" of the European Research Group of hardline Brexit-supporting MPs given that the Cooper-Letwin option was an "unappetising fallback option."

"It is only a situation when the withdrawal agreement has been declared dead that we would reluctantly have to concede that Cooper-Letwin is the only means of buying some extra time to make sure we don't fall off a cliff," said the MP.

An earlier form of the amendment was defeated by 24 votes in parliament in January with all but 17 Conservative MPs voting against it, but a tweaked version is set to return to the Commons in a series of crunch votes on Wednesday.

Another Conservative MP also told Business Insider that a handful of Labour MPs who abstained from voting against the Cooper amendment in January appear ready to back it, while another handful who voted against it now appear ready to abstain.

"If we do have a vote on Cooper-Letwin it will pass," said the MP. "I could easily see amendment being carried by 10 to 14 votes," the MP said.

There is a chance that the amendment will not be put before the Commons at all, as there is a slim chance Theresa May will bring back a revised Brexit deal to parliament before then instead, but Downing Street has dismissed talks of an imminent breakthrough.

Will the 'warning shot' to Brexiteers work?

Jacob Rees-Mogg speaks to the media after submitting a letter of no confidence in Prime Minister Teresa May on November 15, 2018 in London, England. Dan Kitwood / Getty

The prime minister's current Brexit dilemma comes in the form of the European Research Group, the band of Tory MPs led by Jacob Rees-Mogg who say a no-deal Brexit would be preferable to the prime minister's deal.

Many in the ERG, which numbers around 60 MPs, are happy to keep opposing the prime minister's deal because they are relaxed about the alternative.

But the Cooper plan seeks to turn that alternative on its head, and present MPs with a different choice: May's deal or a lengthy Brexit delay, which could mean no Brexit at all.

There are some questions as to whether there is even time for the Cooper plan to work, given threats from Brexit-supporting peers and the tight legislative timetable it would need to squeeze through.

But those backing the plan believe that the Commons and Lords would be able to change their standing orders and force the legislation through if parliament had voted for such a plan.

A win for the amendment would be the start of a lengthy parliamentary process and would not immediately take no deal off the table.

But those Tory MPs threatening to support it believe that a win for the plan on Monday could be enough to bounce Eurosceptic opponents into supporting the withdrawal agreement.

Moderate Tory MPs have certainly detected a softening in tone from their ERG colleagues in recent weeks, and believe some — although not all — are preparing to support the prime minister's deal.

"There are so many ifs and buts in the next few days," said one. "But I'm hoping that people will see the deal that comes back will be just about enough to avoid Cooper-Letwin as a fallback position."

Another told Business Insider last week that "The dynamics among the the ERG [pro-Brexit European Research Group of Conservative MPs] is changing."

"The ERG are splintering and lots of them are coming around to the deal through gritted teeth."

They added: "I say to them 'look you're playing a really dangerous game here that may end up in no Brexit at all' and while some of them still aren't listening to that argument, lots of them are now starting to."