The UK Prime Minister's office has been accused of "overselling" Chancellor Rishi Sunak's Brexit deal.
A critical aspect of the deal, the Windsor framework, will be put to a vote in the UK parliament this week.
Ministers are confident that they have the numbers to get it through, but some in government have raised concerns about the "Stormont brake", which allows the UK government to veto new EU legislation if there are concerns in Northern Ireland.
A minister, who remained unnamed, said that "The legislation isn't what's been sold", referring to the Stormont brake.
Some in government are worried that Downing Street has "overpromised and underdelivered" on this aspect of the Brexit deal.
However, ministers are still confident that they have the support necessary to pass the vote.
One Tory MP, who is opposed to the deal, said that he didn't think the DUP would oppose the Windsor framework.
The Windsor framework is a critical aspect of the Brexit deal, as it is the mechanism that will allow the UK to diverge from EU regulations in specific areas.