Britain's former Brexit secretary Dominic Raab has hit out at the British prime minister Theresa May's withdrawal deal, branding it worse than remaining in the EU.
The prominent Leave backer said the agreement would see the UK bound by rules it had no control over.
Asked if Mrs May's deal was worse than remaining in the bloc, Mr Raab told BBC Radio 4's Today programme: "I'm not going to advocate staying in the EU.
“But, if you just presented me terms, this deal or EU membership, because we would effectively be bound by the same rules but without the control or voice over them, yes, I think this would be even worse than that.”
Mr Raab said the current agreement was unlikely to be passed by the House of Commons, and that ministers should contemplate leaving without one, saying: “We will, I think, inevitably see Parliament vote this deal down.
“And then I think some of those other alternatives will need to come into play.”
The former government minister responsible for the UK’s exit, said the UK would not have to pay the bulk of its £39 billion “divorce bill” if it quit the bloc without a deal.
Mr Raab's comments came as Mrs May was warned she faces a battle to reach a final agreement on Brexit as she prepares for a special summit of European Union leaders this weekend.
Ahead of Sunday's gathering, Spanish premier Pedro Sanchez demanded last-minute changes to the deal despite Mrs May's efforts to win him round.
The British prime minister will head to Brussels on Saturday for eve-of-summit talks with Jean-Claude Juncker knowing that she also faces an uphill task in Westminster to persuade her own MPs to back her deal.
Mrs May declared that final agreement on Brexit is “within our grasp” following a breakthrough on future relations between the UK and European Union on Thursday.
But she endured a bruising session in the House of Commons as critics lined up to condemn both the divorce deal contained in the Withdrawal Agreement and the aspirations for a close future relationship in the Political Declaration.
Ahead of the meeting on Sunday, Taoiseach Leo Varadkar has spoken to Mr Juncker and told him the Dáil has supported the Brexit withdrawal agreement.
Mr Varadkar also said the Government is “happy” with the text of the political declaration, according to the Taoiseach’s spokesman.
At the EU level, a major obstacle remains in the form of Madrid's continued concerns about Gibraltar, with Mr Sanchez vowing to "defend the interests of Spain".
Mrs May said she spoke to Mr Sanchez on Wednesday night and was “confident on Sunday that we’ll be able to agree a deal that delivers for the whole UK family, including Gibraltar”.
But in a late-night tweet on Thursday Mr Sanchez said: "After my conversation with Theresa May, our positions remain far away.
"My Government will always defend the interests of Spain. If there are no changes, we will veto Brexit."
Mr Sanchez cannot “veto Brexit” or the Withdrawal Agreement, but a refusal to co-operate will sour the atmosphere at a summit where leaders of the 27 remaining EU members were aiming for consensus.
Marco Aguiriano, Spain's state secretary for European affairs, said Madrid needs "guarantees we can go on with this model".
“We are asking for an article that is put on the table to be included in the political declaration on the future relations,” he told the BBC.
Chief minister of Gibraltar Fabian Picardo criticised Spain's stance.
He told the BBC: “Spain doesn’t need an article in the treaties, the future declaration, or indeed the withdrawal agreement, to bring Gibraltar to the table.
“Gibraltar has demonstrated that we actually want a direct engagement with Spain on issues.
"Spain is the physical and geographical gateway to Europe for Gibraltar. We recognise that and there is absolutely no need for us to be vetoed into being brought to the table."
Mr Picardo added: "Anybody who says my political view, my political prospectus is that we should drive over this cliff like a political Thelma and Louise isn't thinking about the best interests of the people of the United Kingdom or Gibraltar."
UK education secretary Damian Hinds said he believed support for the prime minister's Brexit deal would grow in parliament as MPs considered the alternatives. He told the BBC: "If we weren't to pass this deal, I think it becomes rather unpredictable what happens next. There is a risk on the one hand beyond that of no Brexit at all — and there are people trying to thwart Brexit — and there is also a risk of no deal." - PA