Brexiteer Tories say the Stormont Brake – a key part of the deal – is “practically useless”.
A group of Eurosceptic Conservative MPs has not yet decided whether to vote against the prime minister’s new Brexit deal for Northern Ireland.
But it has labelled a key element of the deal “practically useless”.
Legal experts have advised the European Research Group (ERG) that EU law will “still be supreme” in Northern Ireland under the deal.
But Downing Street has said there are no plans for substantial changes to what has been agreed.
MPs will vote on the “Stormont Brake” aspect of the deal on Wednesday.
The Democratic Unionist Party (DUP) has already said it will vote against the government’s Windsor Framework plans in Parliament.
The framework replaces the Northern Ireland Protocol, which led to disagreements between the UK and European Union (EU) over trade rules.
The Stormont Brake mechanism aims to give the Northern Ireland a greater say on how EU laws apply to Northern Ireland.
Prime Minister Rishi Sunak said it was proof that the UK has “taken back control” in the agreement he struck with the EU last month.
But the ERG say the Stormont Break is “practically useless” but have declined to say whether they will vote against the deal or not.
ERG chairman Mark Francois told journalists that the “group hasn’t taken the decision yet” on whether to vote against the deal and “it will be down to every individual colleague in that group”.
The European Research Group – known as the ERG – is a group of Eurosceptic Conservative MPs.
The group commissions experts to carry out research about the UK’s relationship with the EU and lobbies the government on issues surrounding Brexit.