The DUP's Sammy Wilson has slammed the slated Brexit deal as a "punishment beating" by the EU on the UK, and said he does not believe PM Theresa May would survive losing a vote in the House of Commons.
The East Antrim MP was speaking ahead of a Cabinet meeting on Wednesday afternoon to discuss the draft text of the Brexit deal, news of which emerged on Tuesday night.
Speaking to Sky News, Mr Wilson said: "This is all about a punishment beating for the UK because they dared to vote to leave the EU. And unfortunately the Prime Minister has allowed that punishment beating to be administered.
"That punishment beating in my belief will damage the UK and damage the UK constitution."
Mr Wilson said his party would not support the agreement.
Although his party has not yet reviewed the full text, this stance was taken on "headlines which have been put into the public domain by the EU", Mr Wilson said, and the deal in its proposed form is "no different to the deal the PM rejected in March and said no PM could ever put her pen to".
Mr Wilson said his party had pushed for a safeguard to be added where the Northern Ireland Assembly, should it be reinstated, would have a veto over Northern Ireland's relationship to the European Union.
"What we would find in the future is that Northern Ireland would have rules about agriculture, labour, production, labour hours, all dictated by Europe," Mr Wilson said.
"We wouldn't have sight of those. We wouldn't even know what they are going to be like in five or six years time, and if they are detrimental to our economy we just have to swallow it."
On the prospect of the deal being voted down in the House of Commons, Mr Wilson said he suspected Theresa May "couldn't survive losing a vote in the House of Commons".
Mr Wilson noted he expected a number of Conservative party backbenchers and Labour MPs to also vote against the deal.