THERESA May’s surprise offer of further compromise on her Chequers deal has been blown out of the water by her Brexit secretary.

Dominic Raab will today tell the party faithful gathered in Birmingham for the annual conference that the Government are prepared “leave without a deal”.

In extracts of his speech released in advance to media, Raab is due to tell members: “We are leaving the European Union in fact, not just in name. If we can’t obtain a deal that secures that objective ... if an attempt is made to lock us in via the back door of the EEA and Customs Union ... or if the only offer from the EU threatens the integrity of our union, then we will be left with no choice but to leave without a deal.”

The Prime Minister had hinted on Sunday that she could re-consider her Brexit deal plans.

She told the Andrew Marr Show: “We need to know what their concerns are,” she said. “This is challenging for the EU and I accept that. It is a deal like no other, they have not done it with anyone else. We believe it does not destroy the single market and we need to have that conversation with them.”

She added: “My mood is to listen to what the EU have to say about their concerns and to sit down and talk them through with them.”

Brexit and May’s authority look set to dominate the conference.

Over the weekend Boris Johnson questioned the Tory leader’s support for Brexit, and calling her Chequers plan “deranged”.

Talking to the Sunday Times, the former Foreign Secretary boasted: “Unlike the Prime Minister I campaigned for Brexit. Unlike the Prime Minister I fought for this, I believe in it, I think it’s the right thing for our country and I think that what is happening now is, alas, not what people were promised in 2016.”

May responded by saying that she was the only one capable of ensuring Brexit could be delivered.

“I do believe in Brexit, but crucially I believe in delivering Brexit in a way that respects the vote and delivers on behalf of the British people, while also protecting our union, protecting jobs and ensuring we make a success of it,” she said.

Johnson, has called for May to back a deal similar to the one the EU has with Canada, even though that would require customs checks on the Northern Irish border.

This he says that process could be simplified with technology. May, however, said that wouldn’t respect the Union.

Scottish Tory leader, Ruth Davidson, made a thinly veiled dig at Johnson during an interview on Sunday morning.

He told The Times that he had not fully appreciated the implications of the withdrawal agreement, where leaders agreed to implement a “backstop” to keep Northern Ireland in the customs union and parts of the single market to avoid a hard border.

“I don’t sit around the Cabinet table, I’m not in government. I do attend political cabinet. But I knew what was being said in December, I’m not quite sure how the Foreign Secretary didn’t,” she said.

Meanwhile, Davidson, who has recently been on a publicity tour to support her new book, was criticised by the SNP’s Alison Thewliss, who accused the Tory leader of adopting a “selective memory”.

The Glasgow Central MP said: “The Scottish Tory Leader’s latest comments on the Rape Clause have been particularly shocking. People in Scotland have literally been taking to the streets to protest against this callous and inhumane policy where victims of rape are forced to make a disclosure and tick a box along side their child’s name to receive tax credits.

“Ruth Davidson has refused to budge on this degrading policy, yet in a Women’s Hour interview she claims to be keen on looking at a ‘better way’ to do it.”