Rishi Sunak has issued a veiled warning to Boris Johnson not to undermine his new Brexit deal - insisting it isn't about "personalities".
The Prime Minister admitted that the controversial Northern Ireland Protocol - signed by Mr Johnson - needed fixing as he mounted a charm offensive to promote his Brexit agreement.
After years of Brexit wrangling, Mr Sunak and EU chief Ursula von der Leyen struck a new deal yesterday aimed at ironing out trading issues in Northern Ireland caused by the UK's departure from the EU.
Mr Sunak travelled to Northern Ireland today, where he told workers in Belfast he was "over the moon" about the progress made.
The new "Windsor Framework" eases checks on goods travelling across the Irish Sea and gives Northern Ireland's politicians a veto on EU law, dubbed the "Stormont brake".
But Mr Sunak must sell the deal to the Democratic Unionist Party and his own Brexiteer backbenchers, including the former Prime Minister.
Mr Johnson has not yet commented, with a source close to him saying he wanted time to study the agreement. Only last week he urged Mr Sunak to stick to his original plan.
The Prime Minister confirmed that he had spoken to Mr Johnson about the deal and issued a veiled warning to his former Cabinet colleague.
Asked if he had briefed Mr Johnson regarding the deal, Mr Sunak told the BBC Radio 4 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.
"This agreement, the Windsor Framework, means that issues that have been raised, the challenges that people faced, those can and will be addressed and that's what I hope people will focus on rather than focusing on the personalities."
Mr Sunak said the deal was an "important step forward" but admitted there was a "small and limited role" for EU law, which may anger Brexiteers.
He also appeared to admit that having access to the EU single market was good for businesses in Northern Ireland - a direct contradiction of the Brexiteers claims that it was better for the UK to be out of the bloc.
"In practical terms, something that is important to people in Northern Ireland is not having a border between Northern Ireland and the Republic, I think that's important to everybody in fact, but also it's important for businesses to have access to the EU single market," he said.
"As long as the people of Northern Ireland consent to that arrangement, then that's why there is a small and limited role for EU law in Northern Ireland - what we are talking about is less than 3% of EU laws that apply in Northern Ireland and they apply very specifically for the purpose that I just mentioned."
Mr Sunak said the real test of the success of the deal will be whether power sharing can be restored at Stormont.
The DUP has been refusing to form an executive in protest at issues with the Northern Ireland Protocol.
DUP leader Sir Jeffrey Donaldson said his party would consider it's response but struck a warmer tone than some of his colleagues.
"We're reasonable people but we want to ensure that what the Prime Minister has said is matched by what is actually in the agreement itself, can it deliver on the areas of concern that we set out in our seven tests?" he told Today.
Sir Jeffrey said Northern Ireland should have unfettered access to the GB market, and if changes to EU law were to impact that, "then it is right that Stormont has a brake and that we're able to ultimately veto any new such law".
He insisted the brake would not be used for "trivial reasons".
"We want to do it in circumstances where a change to law would impact on our ability to trade with the rest of the United Kingdom, and that certainly is no trivial matter," he added.
Speaking at the 1992 Committee of Tory MPs on Tuesday evening the Prime Minister said the DUP should be given "time and space" to consider the deal.
"As you heard in the chamber last night, there are a spectrum of views in their party," Mr Sunak told his own MPs.
"So, let’s not pressure them for an instant answer."
He told MPs present "the last thing the public want is another Westminster drama".
Speaking to reporters outside the Committee room, the Northern Ireland minister and Brexiteer Steve Baker added: "I cannot see how we will get better than this ... this is the deal.
"I'm really clear, there isn't a different deal available, this is what's been negotiated and it's good.
"People are worried about the DUP but there's an earnest sense of relief and support. I think we all believe he's done it, but now we just wait with bated breath to see if the DUP agrees."
