Theresa May’s Brexit deal has taken yet another beating, this time from a cross-party committee which has branded it “neither detailed nor substantive”.

The report from the Exiting the European Union Select Committee adds that it “fails to offer sufficient clarity or certainty about the future” and lacks “realistic, long-term proposals” on the Northern Ireland issue.

Among other points, it says:

• “After 20 months of negotiations, we only know the terms of the UK’s departure but not the nature of the future relationship with the EU. The Prime Minister’s deal fails to offer sufficient clarity or certainty about the future.” 
• “The Political Declaration is neither detailed nor substantive. It only sets out a series of options, and people and businesses will continue to face significant uncertainty about the terms of our trade with the EU after the transitional period ends.”
• “There are no realistic, long-term proposals from the Government to reconcile maintaining an open border on the island of Ireland with leaving the Single Market and Customs Union.”
• “The proposals put forward by the Government to maintain both frictionless trade and an open border – the ’Chequers’ proposals – have been rejected by the EU as unacceptable.” 

The Chair of the Committee, Labour‘s Hilary Benn, said: ”It is because the Government has refused to face up to the hard choices confronting us that this deal would represent a huge step into the unknown.

“The Political Declaration falls far short of the ‘detailed and substantive’ document promised by former Secretaries of State and by the EU Chief Negotiator, Michel Barnier. It does not give the British people or our businesses the clarity and the certainty they need about our future trading relationship with the EU in five or ten years’ time.

“And with these negotiations having not even having started yet, this could take years to sort out.

The report adds to May’s woes ahead of the crucial Commons vote on Tuesday.

On Sunday Boris Johnson refused to rule out challenging her for the Tory leadership as he warned her Brexit deal left the UK open to “blackmail” by Brussels.

The former foreign secretary said it was “nonsense” to suggest he had already begun offering jobs in a future Johnson administration to fellow Tories, but sidestepped the opportunity to promise not to stand against the PM.

He said her Brexit deal could get through the Commons if it was stripped of the backstop measure – an insurance policy to prevent a hard border with Ireland – insisting that would be “relatively simple” to achieve.