Boris Johnson is considering whether to rebel over the post-Brexit deal struck by Rishi Sunak and EU Commission president Ursula von der Leyen.
A source close to the former Tory prime minister said he was studying and reflecting on the Windsor Framework plan to end the Northern Ireland Protocol row.
They did not deny a report that Mr Johnson had asked the DUP to without support until they had looked carefully at the agreement.
The ex-PM contacted the DUP on Monday to ask them to “think hard” about backing it, according to Politics Home. A spokesperson for Mr Johnson said they wouldn’t comment on private discussions.
Mr Sunak phoned Mr Johnson to brief him on the protocol deal and ask him to “pipe down”, one of the PM’s allies told The Telegraph.
Asked if he had spoken to Mr Johnson, Mr Sunak told BBC Radio 4’s Today programme: “Of course I speak to the former prime minister. But this is not about any of us, it is not about personalities, it is not about Westminster. This is about the people of Northern Ireland and what is best for them.”
DUP leader Sir Jeffrey Donaldson warned that “there remain key issues of concern” about Mr Sunak’s deal, while DUP MP Ian Paisley said his gut instinct was that it “doesn’t cut the mustard”.
Tory Brexiteers in the European Research Group (ERG) are to meet on Tuesday evening, and will convene MP Sir Bill Cash’s so-called “star chamber” of lawyers to scrutinise the deal before deciding whether to back it.
Mr Sunak, who is also expected to speak to backbench MPs at the 1922 Committee around 5pm on Tuesday, defended the deal at length as he sought to see off any threat of rebellion from within his own ranks.
Several senior MPs told The Independent they expected a rebellion to be limited to only around 20 MPs – enough for Mr Sunak to get his deal through parliament without relying on Labour support.
Mr Johnson – who last week urged the PM to use his unilateral bill to override the protocol as an alternative to a UK-EU deal – been accused by ex-chancellor George Osborne and others of using the issue to try to “bring down” Mr Sunak.
But the deal has been warmly received by most Tories. One Conservative MP told BBC Newsnight: “This is such a good deal it will finish off Boris. He will have nowhere to go.”
Even Johnson ally and Brexiteer Jacob Rees-Mogg gave the deal a caution welcome, telling ITV’s Peston that Mr Sunak had achieved “more than I thought was possible”.
Mr Rees-Mogg claimed Mr Johnson’s original Brexit agreement was not to blame, claiming the Northern Ireland Protocol had contained “the means for its own amendment”.
Ahead of discussions tonight, Mark Francois, chairman of the ERG, said he hoped that “we won’t find any nasty surprises which would materially undermine the position of Northern Ireland”.
The Independent understands Mr Sunak will give several days before the Commons vote he promised on Monday. One ERG source said they had been told the vote won’t be held this week.
But some supportive MPs fear a delay will give hardliners too much time to discover things they don’t like about the Windsor deal.
Northern Ireland minister and former Brexit rebel Steve Baker was one of the most ardent backers of the deal. “I think this is capable of bringing this awful rollercoaster row to an end, if the DUP are satisfied with it.”
Foreign secretary James Cleverly said it was a “really, really good result”, but said the DUP still needed time and space to consider the details
Asked several times whether the DUP had the power to “scupper” a deal by refusing to return to Stormont, Mr Cleverly told Sky News: “If they don’t re-enter the powersharing executive that would be hugely disappointing. Ultimately we want Stormont up and running.”
Under the deal, anything destined for Northern Ireland will travel there as part of a “green lane”, with significantly fewer checks. Anything that could cross the border and enter the EU’s single market will travel through a separate “red lane”.
Other changes will allow the UK government to set VAT and excise changes for Northern Ireland, rather than the EU. While some EU goods rules will remain in the province, the Sunak government says it means less than 3 per cent of the Brussels rulebook applies.
Under a new arrangement dubbed the “Stormont brake”, Northern Irish politicians get the power to block any unwelcome new EU rules on goods, if 30 MLA signatures from two parties can secure a successful vote. The UK government would then have to support the veto.
However, the European Court of Justice had been final arbitrator of any EU law issues in the region, given the fact that Northern Ireland essentially remains within the single market for goods.
Writing in the Telegraph, chairman of the backbench 1922 committee Sir Graham Brady said: “The so-called Windsor Framework won’t be perfect but it looks like a massive step forward.”
US president Joe Biden said it was an “essential step” in protecting the Good Friday Agreement, while in Dublin Taoiseach Leo Varadkar said that the EU had moved “a lot” to facilitate a deal.