Pro-EU Tory MPs have warned Theresa May they are ready to inflict a damaging Commons defeat on her this week after she failed to reach a compromise deal on the government’s Brexit plans.

Conservative rebels told The Independent that any attempt by ministers to force their flagship Brexit bill through Parliament without further compromise would be a “high-risk gamble and one they will lose”.

The backbenchers are “very confident” they have the numbers to vote down the plans and claimed the number of MPs ready to break cover is growing.

The EU Withdrawal Bill returns to the Commons on Wednesday with the prime minister facing the threat of MPs overturning the government’s proposals for what should happen in the case of a no-deal Brexit.

It will first be debated by the House of Lords on Monday but senior peers said the upper chamber is “100 per cent certain” to reject the government’s proposed compromise.

That would tee up another knife-edge Commons showdown between the prime minister and her backbenchers.

Pro-EU Tories said they were ready to defeat the government and rubbished claims they lack Commons support to do so.

One Conservative rebel told The Independent: “We’ve got the numbers. I’m very confident of that. We would have had the numbers last week.

“If they’re gambling on [winning a Commons vote], that’s a very high-risk gamble and one they will lose. Our numbers are increasing, not diminishing.”

They added: “Throughout these negotiations we’ve been calmly trying to find a common-sense and logical way forward that is in the best interests of the country. We’ve been dialling it down while the hard Brexiteers have been ramping up the rhetoric in the media. It’s disgraceful.”

A Commons defeat would be a major blow for Ms May, who is already facing intense pressure from Brexiteers to prove she is powerful enough to face down her Europhile backbenchers. Eurosceptic Tories and members of her cabinet have made clear they would not accept Parliament being given the right to dictate the terms of Brexit.

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The prime minister staved off a potential rebellion last Tuesday by promising pro-EU MPs she would partially agree to their demands that Parliament be given more powers to block a no-deal Brexit.

However, the resulting motion was described as “unacceptable” by leading Tory rebels, meaning Ms May again faces the prospect of a Commons defeat on Wednesday.

The row centres on what should happen if Parliament votes down the Brexit deal Ms May negotiates with Brussels. Pro-EU rebels want MPs to be given a “meaningful vote” on what should happen if Parliament rejects the deal, but under government plans they would only be allowed to debate the matter, not decide on it.

Around 15 Tory MPs – enough to defeat the government – had threatened to vote through an amendment tabled by Dominic Grieve, the former attorney general, that would give Parliament the power to block a no-deal Brexit and dictate what should happen next.

The rebels temporarily agreed to back down after a last-ditch intervention by Ms May. Meeting with MPs in her Commons office just minutes before the planned vote, the prime minister promised the substance of Mr Grieve’s motion would be included in a government amendment to be tabled in the House of Lords.

Tory MP Stephen Hammond claims Brexit bill is being 'hijacked' by government figures

Tory MP Stephen Hammond claims the Brexit bill is being “hijacked” by government figures. After hours of talks, the backbenchers thought they had reached an agreement with ministers as to the wording of the compromise, but were stunned when the motion that was tabled was significantly different to what they had agreed.

The Independent understands the last-minute change was made after vocal objections from Brexiteers and staunch opposition from David Davis, the Brexit secretary.

The saga led to a breakdown in trust between ministers and pro-EU backbenchers.

One rebel MP said: “I knew they wouldn’t compromise and that is because Theresa May isn’t running the government, David Davis is running the government.

“David Davis is the one who booted out what had been agreed between the solicitor general and Dominic Grieve. Between 3pm and the amendment going down, somebody intervened and Davis said, ‘No I’m not having that – if this goes ahead I’m resigning’. That’s my understanding of what happened.”

“I knew they wouldn’t compromise and that’s because Theresa May isn’t running the government, David Davis is running the government.”

Mr Grieve’s original amendment has now been re-tabled in the Lords by Conservative peer Viscount Hailsham. It is widely expected to pass, while the government’s alternative is set to be comprehensively rejected.

Lord Newby, the Liberal Democrat leader in the Lords, said of the Hailsham amendment: “It is 100 per cent certain to pass. The chances of the government winning on that, given that they lost heavily before, is absolutely zero. I don’t think they stand any chance at all.

“The Tory rebels in the Lords will line up behind Dominic Grieve, we and Labour will line up behind Dominic Grieve and the people who supported the meaningful vote from the crossbenches will do the same, so the government hasn’t got any hope at all of passing their amendment.

“People will line up behind the Hailsham amendment.”

A Labour Lords source confirmed this, saying: “The Dominic Grieve amendment will be heading back to the Commons for MPs to debate. The government amendment is not going to pass.”

And Baroness Hayter, Labour’s shadow Brexit minister, said: “Despite all the advances made, there is a fundamental democratic deficit with the Bill as it stands. It leaves the prime minister – and her very divided Cabinet – able to decide on both our divorce from the EU and future relations without parliamentary approval.

“To deny MPs a truly meaningful vote on the outcome of the Brexit negotiations is unacceptable, and on Monday we will seek to re-insert Dominic Grieve’s wholly sensible amendment.

“We will also move an amendment to ensure that workers, consumers and equality rights and protections cannot be watered down without the express approval of Parliament.”

One Tory MP said it would be a “highly embarrassing reflection on the government” if the Lords pass the Hailsham amendment instead of ministers’ alternative.

Nicky Morgan: Parliament will have a 'real say' if the government fails to secure a Brexit deal

Under the government’s plans, if no deal with Brussels is reached by next January, or if Parliament votes to reject the deal, MPs would be allowed to vote to say they had “considered” the government’s plans for what should happen next.

However, they would not be able to dictate what the next steps should be – something the majority of peers and Tory rebels in the Commons are united in their insistence on.

Mr Grieve’s original proposal said that, if no deal is reached by November or if the deal is rejected, Parliament should be able to vote on the government’s plans for what should happen next.

If there is still no deal by next February, Ms May would have to follow whatever steps Parliament instructs her to take in order to reach an agreement with Brussels before Britain leaves the EU next March.